diff --git a/README.md b/README.md
index 3394f29..586d5a9 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ using it is as simple as adding a single line to Gradle.
 ##### Gradle
 
 ```kotlin
-implementation("org.audux.bgg:bggclient:0.6.0")
+implementation("org.audux.bgg:bggclient:0.8.0")
 ```
 
 ##### Maven
@@ -35,7 +35,7 @@ implementation("org.audux.bgg:bggclient:0.6.0")
 <dependency>
     <groupId>org.audux.bgg</groupId>
     <artifactId>bggclient</artifactId>
-    <version>0.6.0</version>
+    <version>0.8.0</version>
 </dependency>
 ```
 
diff --git a/build.gradle.kts b/build.gradle.kts
index 1fafe7d..9a65890 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -7,6 +7,7 @@ plugins {
     `maven-publish`
     signing
     alias(libs.plugins.com.gradleup.nmcp)
+    alias(libs.plugins.kotlin.serialization)
     alias(libs.plugins.ktfmt.gradle)
     alias(libs.plugins.org.jetbrains.dokka)
     alias(libs.plugins.org.jetbrains.kotlin.jvm)
@@ -22,7 +23,7 @@ publishing {
         create<MavenPublication>("mavenJava") {
             groupId = "org.audux.bgg"
             artifactId = "bggclient"
-            version = "0.6.0"
+            version = "0.8.0"
 
             pom {
                 name = "Unofficial JVM BGG client"
@@ -100,6 +101,7 @@ dependencies {
     // Testing dependencies.
     testApi(libs.ktor.client.mock)
 
+    testImplementation(libs.kotlin.serialization.json)
     testImplementation(libs.junit5.jupiter)
     testImplementation(libs.junit5.params)
     testImplementation(libs.truth)
diff --git a/examples/android/app/build.gradle.kts b/examples/android/app/build.gradle.kts
index 6063c74..c6ebce2 100644
--- a/examples/android/app/build.gradle.kts
+++ b/examples/android/app/build.gradle.kts
@@ -68,7 +68,7 @@ dependencies {
     implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
     implementation("androidx.lifecycle:lifecycle-viewmodel-compose:2.7.0")
     implementation("io.coil-kt:coil-compose:2.5.0")
-    implementation("org.audux.bgg:bggclient:0.6.0")
+    implementation("org.audux.bgg:bggclient:0.8.0")
 
     testImplementation("junit:junit:4.13.2")
 
diff --git a/examples/java/build.gradle.kts b/examples/java/build.gradle.kts
index 3404827..738f184 100644
--- a/examples/java/build.gradle.kts
+++ b/examples/java/build.gradle.kts
@@ -12,7 +12,7 @@ repositories {
 }
 
 dependencies {
-    implementation("org.audux.bgg:bggclient:0.6.0")
+    implementation("org.audux.bgg:bggclient:0.8.0")
 
     testImplementation(platform("org.junit:junit-bom:5.9.1"))
     testImplementation("org.junit.jupiter:junit-jupiter")
diff --git a/examples/paginate/build.gradle.kts b/examples/paginate/build.gradle.kts
index d4da7d5..8bbdba7 100644
--- a/examples/paginate/build.gradle.kts
+++ b/examples/paginate/build.gradle.kts
@@ -20,7 +20,7 @@ application {
 }
 
 dependencies {
-    implementation("org.audux.bgg:bggclient:0.6.0")
+    implementation("org.audux.bgg:bggclient:0.8.0")
 
     testImplementation("org.jetbrains.kotlin:kotlin-test")
 }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 43e5152..e5b9942 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -9,7 +9,7 @@ ktor = "2.3.8"
 org-jetbrains-dokka = "1.9.10"
 org-jetbrains-kotlin-jvm = "1.9.22"
 org-jetbrains-kotlin-jdk8 = "1.8.0"
-serialization = "1.6.3"
+serialization = "1.5.0"
 slf4j = "2.0.12"
 truth = "1.4.1"
 
@@ -24,6 +24,7 @@ junit5-params = { module = "org.junit.jupiter:junit-jupiter-params", version.ref
 kermit = { module = "co.touchlab:kermit", version.ref = "kermit" }
 kotlin-coroutines-jdk8 = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-jdk8", version.ref = "org-jetbrains-kotlin-jdk8" }
 kotlin-serialization = { module = "org.jetbrains.kotlinx:kotlinx-serialization-core", version.ref = "serialization" }
+kotlin-serialization-json = { module = "org.jetbrains.kotlinx:kotlinx-serialization-json-jvm", version.ref = "serialization" }
 ktor-core = { module = "io.ktor:ktor-client-core", version.ref = "ktor" }
 ktor-client = { module = "io.ktor:ktor-client-cio", version.ref = "ktor" }
 ktor-client-mock = { module = "io.ktor:ktor-client-mock", version.ref = "ktor" }
@@ -35,4 +36,5 @@ org-jetbrains-kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "org
 ktfmt-gradle = { id = "com.ncorti.ktfmt.gradle", version.ref = "ktfmt-gradle" }
 com-gradleup-nmcp = { id = "com.gradleup.nmcp", version.ref = "com-gradleup-nmcp" }
 org-jetbrains-dokka = { id = "org.jetbrains.dokka", version.ref = "org-jetbrains-dokka" }
+kotlin-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "org-jetbrains-kotlin-jvm" }
 
diff --git a/src/main/kotlin/org/audux/bgg/common/Types.kt b/src/main/kotlin/org/audux/bgg/common/Types.kt
index f844402..06415ff 100644
--- a/src/main/kotlin/org/audux/bgg/common/Types.kt
+++ b/src/main/kotlin/org/audux/bgg/common/Types.kt
@@ -16,6 +16,7 @@ package org.audux.bgg.common
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
+import kotlinx.serialization.Serializable
 import org.audux.bgg.response.WrappedDoubleDeserializer
 import org.audux.bgg.response.WrappedIntDeserializer
 
@@ -23,6 +24,7 @@ import org.audux.bgg.response.WrappedIntDeserializer
  * The different kind/type of things the API may return such as a board game or expansion etc.
  * [See docs for more info](https://boardgamegeek.com/wiki/page/BGG_XML_API2#Thing_Items).
  */
+@Serializable
 enum class ThingType(val param: String) {
     UNKNOWN(""), // Used whenever the type is empty or not recognized.
     BOARD_GAME("boardgame"),
@@ -47,6 +49,7 @@ enum class ThingType(val param: String) {
  *
  * Note: About half of these types actually do _not_ return any list.
  */
+@Serializable
 enum class HotListType(val param: String) {
     UNKNOWN(""), // Used whenever the type is empty or not recognized.
     BOARD_GAME("boardgame"),
@@ -60,6 +63,7 @@ enum class HotListType(val param: String) {
 }
 
 /** Different sub types returned in the [org.audux.bgg.request.plays] request/ response */
+@Serializable
 enum class SubType(val param: String) {
     UNKNOWN(""), // Used whenever the type is empty or not recognized.
     BOARD_GAME("boardgame"),
@@ -81,6 +85,7 @@ enum class SubType(val param: String) {
  * The different kind/type of families the API may return such as a board game or rpgs.
  * [See docs for more info](https://boardgamegeek.com/wiki/page/BGG_XML_API2#Family_Items).
  */
+@Serializable
 enum class FamilyType(val param: String) {
     UNKNOWN(""), // Used whenever the type is empty or not recognized.
     RPG("rpg"),
@@ -96,6 +101,7 @@ enum class FamilyType(val param: String) {
  * Used to map the id in the forumlist request to either a family ot thing.
  * [See docs for more info](https://boardgamegeek.com/wiki/page/BGG_XML_API2#Forum_Lists).
  */
+@Serializable
 enum class ForumListType(val param: String) {
     UNKNOWN(""), // Used whenever the type is empty or not recognized.
     THING("thing"),
@@ -107,6 +113,7 @@ enum class ForumListType(val param: String) {
 }
 
 /** Used to show what type of thing it is when played, either a thing or a family(?) */
+@Serializable
 enum class PlayThingType(val param: String) {
     UNKNOWN(""), // Used whenever the type is empty or not recognized.
     THING("thing"),
@@ -121,6 +128,7 @@ enum class PlayThingType(val param: String) {
  * Used to either include or exclude certain items in a request, see
  * [org.audux.bgg.request.collection] and [org.audux.bgg.request.user].
  */
+@Serializable
 enum class Inclusion {
     INCLUDE,
     EXCLUDE;
@@ -129,6 +137,7 @@ enum class Inclusion {
 }
 
 /** Different domains used for the users' hot- and top-10. */
+@Serializable
 enum class Domain(val param: String, val address: String) {
     BOARD_GAME_GEEK("boardgame", "https://boardgamegeek.com"),
     RPG_GEEK("rpg", "https://rpggeek.com"),
@@ -136,6 +145,7 @@ enum class Domain(val param: String, val address: String) {
 }
 
 /** Encapsulates the name of a Thing either primary or alternate name. */
+@Serializable
 data class Name(
     /** The actual name. */
     @JacksonXmlProperty(isAttribute = true) val value: String,
@@ -151,6 +161,7 @@ data class Name(
 )
 
 /** Wrapper for [Ratings]. */
+@Serializable
 data class Statistics(
     /** Unused attribute? */
     @JacksonXmlProperty(isAttribute = true) val page: Int?,
@@ -163,6 +174,7 @@ data class Statistics(
  * Contains rating aggregated and other statistics like average rating, standard deviation, number
  * of comments.
  */
+@Serializable
 data class Ratings(
     /** A user rating if available. */
     @JacksonXmlProperty(isAttribute = true) val value: String? = null,
@@ -211,6 +223,7 @@ data class Ratings(
 )
 
 /** Represents a rank in a single ranking (Consisting of type & name). */
+@Serializable
 data class Rank(
     /** Unique of the ranking type - ID and type+name should always be a coupled. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -248,6 +261,7 @@ data class Rank(
  *
  *   And so on.
  */
+@Serializable
 data class Link(
     /**
      * The id for the link, most of these cannot be retrieved via the API although a 'family'-API
diff --git a/src/main/kotlin/org/audux/bgg/response/Collection.kt b/src/main/kotlin/org/audux/bgg/response/Collection.kt
index aa460e7..1613e38 100644
--- a/src/main/kotlin/org/audux/bgg/response/Collection.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Collection.kt
@@ -19,6 +19,7 @@ import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDateTime
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.Ratings
 import org.audux.bgg.common.ThingType
 
@@ -26,6 +27,7 @@ import org.audux.bgg.common.ThingType
  * Response wrapper for the user's Collection. These contain lists of items like board games wrapped
  * in [CollectionItem].
  */
+@Serializable
 @JsonRootName("items")
 data class Collection(
     /** Terms of use of the BGG API. */
@@ -43,6 +45,7 @@ data class Collection(
 
 /** An item in the collection e.g. a board game, rpg etc. */
 @JsonIgnoreProperties("objecttype")
+@Serializable
 data class CollectionItem(
     @JacksonXmlProperty(isAttribute = true, localName = "collid") val collectionId: Int,
     @JacksonXmlProperty(isAttribute = true) val objectId: Int,
@@ -84,6 +87,7 @@ data class CollectionItem(
 )
 
 /** The status of collection item e.g. whether the user owns it, wants it etc. */
+@Serializable
 data class Status(
     /** Whether item is currently owned. */
     @JsonDeserialize(using = NumberToBooleanDeserializer::class)
@@ -131,10 +135,12 @@ data class Status(
     /** Whether item is currently owned. */
     @JacksonXmlProperty(isAttribute = true)
     @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
+    @Serializable(with = LocalDateTimeSerializer::class)
     val lastModified: LocalDateTime? = null,
 )
 
 /** Statistics for a collection item. */
+@Serializable
 data class CollectionStatistics(
     /** Minimum number of players. */
     @JacksonXmlProperty(localName = "minplayers") val minimumPlayers: Int?,
diff --git a/src/main/kotlin/org/audux/bgg/response/Family.kt b/src/main/kotlin/org/audux/bgg/response/Family.kt
index b9891ae..5695c6b 100644
--- a/src/main/kotlin/org/audux/bgg/response/Family.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Family.kt
@@ -16,12 +16,14 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.FamilyType
 import org.audux.bgg.common.Link
 import org.audux.bgg.common.Name
 
 /** Response wrapper for Family items, e.g. games having a related theme or gameplay. */
 @JsonRootName("items")
+@Serializable
 data class Family(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -31,6 +33,7 @@ data class Family(
 )
 
 /** The actual Family item e.g. a `boardgamefamily`, rpg etc. */
+@Serializable
 data class FamilyItem(
     /** Unique ID that can be used to look up more information using the thing endpoint. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
diff --git a/src/main/kotlin/org/audux/bgg/response/Forum.kt b/src/main/kotlin/org/audux/bgg/response/Forum.kt
index 8a2406d..d036ea3 100644
--- a/src/main/kotlin/org/audux/bgg/response/Forum.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Forum.kt
@@ -19,12 +19,14 @@ import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDateTime
+import kotlinx.serialization.Serializable
 
 /**
  * Encapsulates a forum containing a list of thread summaries - these can be retrieve using in
  * [org.audux.bgg.request.thread] endpoint.
  */
 @JsonRootName("forum")
+@Serializable
 data class Forum(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -51,6 +53,7 @@ data class Forum(
     /** The date and time a post was last made. */
     @JsonFormat(pattern = "E, dd MMM yyyy HH:mm:ss Z")
     @JacksonXmlProperty(isAttribute = true)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val lastPostDate: LocalDateTime?,
 
     /** The list of threads in this forum. */
@@ -60,6 +63,7 @@ data class Forum(
 /**
  * Summary of a thread in the forum, contains some stats and aggregated data but no articles/posts.
  */
+@Serializable
 data class ThreadSummary(
     /** Unique ID that can be used to look up more information using the thread endpoint. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -80,10 +84,12 @@ data class ThreadSummary(
     /** The date and time this thread was created. */
     @JsonFormat(pattern = "E, dd MMM yyyy HH:mm:ss Z")
     @JacksonXmlProperty(isAttribute = true)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val postDate: LocalDateTime?,
 
     /** The date and time a post was last made in this thread. */
     @JsonFormat(pattern = "E, dd MMM yyyy HH:mm:ss Z")
     @JacksonXmlProperty(isAttribute = true)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val lastPostDate: LocalDateTime?,
 )
diff --git a/src/main/kotlin/org/audux/bgg/response/ForumList.kt b/src/main/kotlin/org/audux/bgg/response/ForumList.kt
index 45e362e..60dd21c 100644
--- a/src/main/kotlin/org/audux/bgg/response/ForumList.kt
+++ b/src/main/kotlin/org/audux/bgg/response/ForumList.kt
@@ -18,10 +18,12 @@ import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDateTime
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.ForumListType
 
 /** Response wrapper for a list of forums for the given id/thing pair. */
 @JsonRootName("forums")
+@Serializable
 data class ForumList(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -42,6 +44,7 @@ data class ForumList(
  * Encapsulates the summary of a forum - these can be retrieve using the
  * [org.audux.bgg.request.forum] endpoint.
  */
+@Serializable
 data class ForumSummary(
     /** Unique ID that can be used to look up more information using the forum endpoint. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -73,5 +76,6 @@ data class ForumSummary(
     /** The date and time a post was last made. */
     @JsonFormat(pattern = "E, dd MMM yyyy HH:mm:ss Z")
     @JacksonXmlProperty(isAttribute = true)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val lastPostDate: LocalDateTime?,
 )
diff --git a/src/main/kotlin/org/audux/bgg/response/GeekList.kt b/src/main/kotlin/org/audux/bgg/response/GeekList.kt
index 6a27bc6..37f4274 100644
--- a/src/main/kotlin/org/audux/bgg/response/GeekList.kt
+++ b/src/main/kotlin/org/audux/bgg/response/GeekList.kt
@@ -17,15 +17,18 @@ import com.fasterxml.jackson.annotation.JsonFormat
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties
 import com.fasterxml.jackson.annotation.JsonProperty
 import com.fasterxml.jackson.annotation.JsonRootName
+import com.fasterxml.jackson.annotation.JsonSetter
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlText
 import java.time.LocalDateTime
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.Constants
 
 /** Encapsulates a geek list including its items and optionally its comments. */
 @JsonRootName("geeklist")
 @JsonIgnoreProperties("postdate_timestamp", "editdate_timestamp")
+@Serializable
 data class GeekList(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -34,10 +37,14 @@ data class GeekList(
     @JacksonXmlProperty(isAttribute = true) val id: Int,
 
     /** The date and time the geek list was posted/published. */
-    @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT) val postDate: LocalDateTime,
+    @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
+    @Serializable(with = LocalDateTimeSerializer::class)
+    val postDate: LocalDateTime,
 
     /** The date and time the geek list was last edited - the same as [postDate] if not edited. */
-    @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT) val editDate: LocalDateTime,
+    @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
+    @Serializable(with = LocalDateTimeSerializer::class)
+    val editDate: LocalDateTime,
 
     /** The number of thumbs up/likes the geek list received. */
     val thumbs: Int,
@@ -66,6 +73,7 @@ data class GeekList(
 }
 
 /** A single comment on either a Geek list or a Geek list item. */
+@Serializable
 data class GeekListComment(
     /** The username of the user that left the comment. */
     @JacksonXmlProperty(isAttribute = true) val username: String,
@@ -73,16 +81,19 @@ data class GeekListComment(
     /** The date the comment was originally posted. */
     @JacksonXmlProperty(isAttribute = true)
     @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val date: LocalDateTime,
 
     /** The date the comment was originally posted. */
     @JacksonXmlProperty(isAttribute = true)
     @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val postDate: LocalDateTime,
 
     /** The date the comment was last edited - the same as [postDate] if not edited. */
     @JacksonXmlProperty(isAttribute = true)
     @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val editDate: LocalDateTime,
 
     /** The number of thumbs up/likes on this item. */
@@ -97,6 +108,7 @@ data class GeekListComment(
 }
 
 /** An item in the geek list e.g. a board game including a description/[body] */
+@Serializable
 data class GeekListItem(
     /** The ID of the geek list item - NOT the id of the object. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -124,11 +136,13 @@ data class GeekListItem(
     /** The original date this item was added/posted to the list. */
     @JacksonXmlProperty(isAttribute = true)
     @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val postDate: LocalDateTime,
 
     /** The date this item was last edited/changed. */
     @JacksonXmlProperty(isAttribute = true)
     @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val editDate: LocalDateTime,
 
     /** The number of thumbs up/likes this item has received. */
@@ -140,11 +154,12 @@ data class GeekListItem(
      */
     @JacksonXmlProperty(isAttribute = true) val imageId: Int? = null,
     @JsonDeserialize(using = TrimmedStringDeserializer::class) val body: String,
-) {
+
     /** The list of comments of this list. */
-    @JsonProperty("comment")
-    var comments: List<GeekListComment> = mutableListOf()
-        set(value) {
-            field = field + value
-        }
+    var comments: List<GeekListComment> = mutableListOf(),
+) {
+    @JsonSetter("comment")
+    fun internalSetComment(value: List<GeekListComment>) {
+        comments = comments + value
+    }
 }
diff --git a/src/main/kotlin/org/audux/bgg/response/Guild.kt b/src/main/kotlin/org/audux/bgg/response/Guild.kt
index 0522119..e223c72 100644
--- a/src/main/kotlin/org/audux/bgg/response/Guild.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Guild.kt
@@ -18,10 +18,12 @@ import com.fasterxml.jackson.annotation.JsonProperty
 import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDateTime
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.Constants
 
 /** Response wrapper for Guilds to be returned. */
 @JsonRootName("guild")
+@Serializable
 data class Guild(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -35,6 +37,7 @@ data class Guild(
     /** The date and time the guild was created. */
     @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
     @JacksonXmlProperty(isAttribute = true, localName = "created")
+    @Serializable(with = LocalDateTimeSerializer::class)
     val createdAt: LocalDateTime?,
 
     /** The category of the Guild e.g. an interest group, regional group etc. */
@@ -57,6 +60,7 @@ data class Guild(
 )
 
 /** The physical location of the guild. */
+@Serializable
 data class Location(
     /** First address line. */
     @JsonProperty("addr1") val addressLine1: String,
@@ -78,6 +82,7 @@ data class Location(
 )
 
 /** Represents a (partial) list of members of the guild. */
+@Serializable
 data class GuildMembers(
     /** The total number of guild members. */
     @JacksonXmlProperty(isAttribute = true) val count: Int,
@@ -97,6 +102,7 @@ data class GuildMembers(
  * A GuildMember entry, consisting of simply a username (can be used to retrieve more user info) and
  * a join date and time.
  */
+@Serializable
 data class GuildMember(
     /** The username of the guild member. */
     @JacksonXmlProperty(isAttribute = true) val name: String,
@@ -104,5 +110,6 @@ data class GuildMember(
     /** When the user joined the guild. */
     @JsonFormat(pattern = Constants.DAY_FIRST_DATE_TIME_FORMAT)
     @JacksonXmlProperty(isAttribute = true, localName = "date")
+    @Serializable(with = LocalDateTimeSerializer::class)
     val joinDate: LocalDateTime,
 )
diff --git a/src/main/kotlin/org/audux/bgg/response/HotList.kt b/src/main/kotlin/org/audux/bgg/response/HotList.kt
index db7f6f2..e123cd2 100644
--- a/src/main/kotlin/org/audux/bgg/response/HotList.kt
+++ b/src/main/kotlin/org/audux/bgg/response/HotList.kt
@@ -16,9 +16,11 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
+import kotlinx.serialization.Serializable
 
 /** Response wrapper for Hot lists to be returned. */
 @JsonRootName("items")
+@Serializable
 data class HotList(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -28,6 +30,7 @@ data class HotList(
 )
 
 /** Encapsulates a ranked item in the hot list. */
+@Serializable
 data class HotListItem(
     /** Unique ID that can be used to look up more information using the thing endpoint. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
diff --git a/src/main/kotlin/org/audux/bgg/response/TypeDeserializers.kt b/src/main/kotlin/org/audux/bgg/response/JsonDeserializers.kt
similarity index 100%
rename from src/main/kotlin/org/audux/bgg/response/TypeDeserializers.kt
rename to src/main/kotlin/org/audux/bgg/response/JsonDeserializers.kt
diff --git a/src/main/kotlin/org/audux/bgg/response/KSerializers.kt b/src/main/kotlin/org/audux/bgg/response/KSerializers.kt
new file mode 100644
index 0000000..1c3740f
--- /dev/null
+++ b/src/main/kotlin/org/audux/bgg/response/KSerializers.kt
@@ -0,0 +1,80 @@
+package org.audux.bgg.response
+
+import java.net.URI
+import java.time.LocalDate
+import java.time.LocalDateTime
+import kotlinx.serialization.InternalSerializationApi
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.SealedClassSerializer
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+
+/** [KSerializer] for a [LocalDate]. */
+internal class LocalDateSerializer : KSerializer<LocalDate> {
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor("LocalDate", PrimitiveKind.STRING)
+
+    override fun serialize(encoder: Encoder, value: LocalDate) {
+        encoder.encodeString(value.toString())
+    }
+
+    override fun deserialize(decoder: Decoder): LocalDate = LocalDate.parse(decoder.decodeString())
+}
+
+/** [KSerializer] for a [LocalDateTime]. */
+internal class LocalDateTimeSerializer : KSerializer<LocalDateTime> {
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor("LocalDateTime", PrimitiveKind.STRING)
+
+    override fun serialize(encoder: Encoder, value: LocalDateTime) {
+        encoder.encodeString(value.toString())
+    }
+
+    override fun deserialize(decoder: Decoder): LocalDateTime =
+        LocalDateTime.parse(decoder.decodeString())
+}
+
+/** [KSerializer] for a [URI]. */
+internal class URISerializer : KSerializer<URI> {
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor("URI", PrimitiveKind.STRING)
+
+    override fun serialize(encoder: Encoder, value: URI) {
+        encoder.encodeString(value.toString())
+    }
+
+    override fun deserialize(decoder: Decoder): URI = URI.create(decoder.decodeString())
+}
+
+/** [KSerializer] for [Poll] and all sub-classes. */
+@OptIn(InternalSerializationApi::class)
+internal class PollSerializer : KSerializer<Poll> {
+    private val serializer =
+        SealedClassSerializer(
+            "Poll",
+            Poll::class,
+            arrayOf(
+                LanguageDependencePoll::class,
+                PlayerAgePoll::class,
+                NumberOfPlayersPoll::class
+            ),
+            arrayOf(
+                LanguageDependencePoll.serializer(),
+                PlayerAgePoll.serializer(),
+                NumberOfPlayersPoll.serializer(),
+            ),
+        )
+
+    override val descriptor: SerialDescriptor = serializer.descriptor
+
+    override fun deserialize(decoder: Decoder): Poll {
+        return serializer.deserialize(decoder)
+    }
+
+    override fun serialize(encoder: Encoder, value: Poll) {
+        serializer.serialize(encoder, value)
+    }
+}
diff --git a/src/main/kotlin/org/audux/bgg/response/Plays.kt b/src/main/kotlin/org/audux/bgg/response/Plays.kt
index a78f33f..65c69e4 100644
--- a/src/main/kotlin/org/audux/bgg/response/Plays.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Plays.kt
@@ -18,10 +18,12 @@ import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDate
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.PlayThingType
 
 /** Response wrapper for plays by the user to be returned. */
 @JsonRootName("plays")
+@Serializable
 data class Plays(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -46,12 +48,15 @@ data class Plays(
  * Represents a single(or batched as specified by `quantity`) play, including the 'thing'/game and
  * its players.
  */
+@Serializable
 data class Play(
     /** Unique ID of the play - not used */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
 
     /** The date the play took place. */
-    @JacksonXmlProperty(isAttribute = true) val date: LocalDate,
+    @JacksonXmlProperty(isAttribute = true)
+    @Serializable(with = LocalDateSerializer::class)
+    val date: LocalDate,
 
     /** The number of plays, of the same game with the same players. */
     @JacksonXmlProperty(isAttribute = true) val quantity: Int,
@@ -86,6 +91,7 @@ data class Play(
 )
 
 /** Represents the item/thing that was played e.g. a board game. */
+@Serializable
 data class PlayItem(
     /** The name of the item. */
     @JacksonXmlProperty(isAttribute = true) val name: String,
@@ -107,6 +113,7 @@ data class PlayItem(
 )
 
 /** A SubType of a thing e.g. board game. */
+@Serializable
 data class SubType(
     @JsonDeserialize(using = WrappedSubTypeDeserializer::class)
     val subtype: org.audux.bgg.common.SubType
@@ -116,6 +123,7 @@ data class SubType(
  * Represents a person in the play i.e. their username, id, what color they played, how they did
  * etc.
  */
+@Serializable
 data class Player(
     /** Optional username of the player. */
     @JacksonXmlProperty(isAttribute = true) val username: String?,
diff --git a/src/main/kotlin/org/audux/bgg/response/Search.kt b/src/main/kotlin/org/audux/bgg/response/Search.kt
index c081fd8..68f2652 100644
--- a/src/main/kotlin/org/audux/bgg/response/Search.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Search.kt
@@ -16,11 +16,13 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.Name
 import org.audux.bgg.common.ThingType
 
 /** Response wrapper for the search results/items to be returned. */
 @JsonRootName("items")
+@Serializable
 data class SearchResults(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -33,6 +35,7 @@ data class SearchResults(
 )
 
 /** Encapsulates a single search result. */
+@Serializable
 data class SearchResult(
     /** Primary or alternative name. */
     val name: Name,
diff --git a/src/main/kotlin/org/audux/bgg/response/Sitemap.kt b/src/main/kotlin/org/audux/bgg/response/Sitemap.kt
index 57d480b..c07107e 100644
--- a/src/main/kotlin/org/audux/bgg/response/Sitemap.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Sitemap.kt
@@ -19,10 +19,12 @@ import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDate
+import kotlinx.serialization.Serializable
 
 /** Represents a single Sitemap containing a set of URLs. */
 @JsonRootName("urlset")
 @JsonIgnoreProperties("schemaLocation")
+@Serializable
 data class Sitemap(
     /** List of the URLs in this Sitemap. */
     @JacksonXmlProperty(localName = "url") val sitemaps: List<SitemapUrl>
@@ -32,6 +34,7 @@ data class Sitemap(
  * Single URL/Location contained in the Sitemap; could, for example, represent a single Board game
  * page.
  */
+@Serializable
 data class SitemapUrl(
     /** The actual URL/Web address */
     @JsonProperty("loc")
@@ -45,5 +48,7 @@ data class SitemapUrl(
     val priority: Double?,
 
     /** The date the page was last modified. */
-    @JsonProperty("lastmod") val lastModified: LocalDate?,
+    @JsonProperty("lastmod")
+    @Serializable(with = LocalDateSerializer::class)
+    val lastModified: LocalDate?,
 )
diff --git a/src/main/kotlin/org/audux/bgg/response/SitemapIndex.kt b/src/main/kotlin/org/audux/bgg/response/SitemapIndex.kt
index 636ddad..3ca6037 100644
--- a/src/main/kotlin/org/audux/bgg/response/SitemapIndex.kt
+++ b/src/main/kotlin/org/audux/bgg/response/SitemapIndex.kt
@@ -18,6 +18,7 @@ import com.fasterxml.jackson.annotation.JsonProperty
 import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.SitemapLocationType
 
 /**
@@ -26,12 +27,14 @@ import org.audux.bgg.common.SitemapLocationType
  */
 @JsonRootName("sitemapindex")
 @JsonIgnoreProperties("schemaLocation")
+@Serializable
 data class SitemapIndex(
     /** List of sitemap locations. */
     @JacksonXmlProperty(localName = "sitemap") val sitemaps: List<SitemapLocation>
 )
 
 /** A URL/Location of a single sitemap/sitemap page. */
+@Serializable
 data class SitemapLocation(
     /** The URL/Web address of the sitemap. */
     @JsonProperty("loc")
diff --git a/src/main/kotlin/org/audux/bgg/response/Things.kt b/src/main/kotlin/org/audux/bgg/response/Things.kt
index 438d7be..45f5a19 100644
--- a/src/main/kotlin/org/audux/bgg/response/Things.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Things.kt
@@ -17,6 +17,7 @@ import com.fasterxml.jackson.annotation.JsonFormat
 import com.fasterxml.jackson.annotation.JsonIgnore
 import com.fasterxml.jackson.annotation.JsonProperty
 import com.fasterxml.jackson.annotation.JsonRootName
+import com.fasterxml.jackson.annotation.JsonSetter
 import com.fasterxml.jackson.annotation.JsonSubTypes
 import com.fasterxml.jackson.annotation.JsonTypeInfo
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
@@ -25,12 +26,14 @@ import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.net.URI
 import java.time.LocalDate
 import java.time.LocalDateTime
+import kotlinx.serialization.Serializable
 import org.audux.bgg.common.Link
 import org.audux.bgg.common.Name
 import org.audux.bgg.common.Statistics
 import org.audux.bgg.common.ThingType
 
 /** Response wrapper for the things to be returned. */
+@Serializable
 @JsonRootName("items")
 data class Things(
     /** Terms of use of the BGG API. */
@@ -52,6 +55,7 @@ data class Things(
  *
  * @see org.audux.bgg.request.things
  */
+@Serializable
 data class Thing(
     /** Unique BGG identifier. */
     val id: Int,
@@ -83,7 +87,9 @@ data class Thing(
     @JsonDeserialize(using = WrappedStringDeserializer::class) val datePublished: String?,
 
     /** The year it was released in e.g. `2019`. (For video games) */
-    @JsonDeserialize(using = WrappedLocalDateDeserializer::class) val releaseDate: LocalDate?,
+    @JsonDeserialize(using = WrappedLocalDateDeserializer::class)
+    @Serializable(with = LocalDateSerializer::class)
+    val releaseDate: LocalDate?,
 
     /** Minimum number of players required. */
     @JsonDeserialize(using = WrappedIntDeserializer::class) val minPlayers: Int?,
@@ -138,88 +144,40 @@ data class Thing(
     @JsonDeserialize(using = WrappedIntDeserializer::class) val issueIndex: Int?,
 
     /** Primary name. */
-    @JsonIgnore var name: String = ""
-) {
+    @JsonIgnore var name: String = "",
+
     /** Contains a list of polls such as the [PlayerAgePoll]. */
-    @JsonProperty("poll")
-    var polls: List<Poll> = listOf()
-        set(value) {
-            field = field + value
-        }
+    var polls: List<Poll> = listOf(),
 
     /**
      * Depending on the [type] this list may contain different links e.g. for boardgames links such
      * as: `boardgamecategory`, `boardgamefamily`, `boardgamemechanic` etc. may be included. For
      * `rpgitem` similar but different links are returned e.g. `rpgitemcategory` etc.
      */
-    @JacksonXmlProperty(localName = "link")
-    var links: List<Link> = listOf()
-        set(value) {
-            field = field + value
-        }
+    var links: List<Link> = listOf(),
 
     /** Names of the thing, consisting of a primary and optionally alternatives. */
-    @JsonProperty("name")
-    var names: List<Name> = listOf()
-        set(value) {
-            field = field + value
-            field.forEach { if (it.type == "primary") name = it.value }
-        }
-
-    fun copy(
-        id: Int = this.id,
-        type: ThingType = this.type,
-        thumbnail: String? = this.thumbnail,
-        image: String? = this.image,
-        description: String? = this.description,
-        yearPublished: Int? = this.yearPublished,
-        datePublished: String? = this.datePublished,
-        releaseDate: LocalDate? = this.releaseDate,
-        minPlayers: Int? = this.minPlayers,
-        maxPlayers: Double? = this.maxPlayers,
-        playingTimeInMinutes: Int? = this.playingTimeInMinutes,
-        minPlayingTimeInMinutes: Int? = this.minPlayingTimeInMinutes,
-        maxPlayingTimeInMinutes: Int? = this.maxPlayingTimeInMinutes,
-        minAge: Int? = this.minAge,
-        videos: List<Video> = this.videos,
-        comments: Comments? = this.comments,
-        statistics: Statistics? = this.statistics,
-        listings: List<MarketplaceListing> = this.listings,
-        versions: List<Version> = this.versions,
-        seriesCode: String? = this.seriesCode,
-        issueIndex: Int? = this.issueIndex
-    ) =
-        Thing(
-                id,
-                type,
-                thumbnail,
-                image,
-                description,
-                yearPublished,
-                datePublished,
-                releaseDate,
-                minPlayers,
-                maxPlayers,
-                playingTimeInMinutes,
-                minPlayingTimeInMinutes,
-                maxPlayingTimeInMinutes,
-                minAge,
-                videos,
-                comments,
-                statistics,
-                listings,
-                versions,
-                seriesCode,
-                issueIndex,
-            )
-            .also {
-                it.names = this.names
-                it.links = this.links
-                it.polls = this.polls
-            }
+    var names: List<Name> = listOf(),
+) {
+    @JsonSetter("poll")
+    fun internalSetPolls(value: List<Poll>) {
+        polls = polls + value
+    }
+
+    @JsonSetter("link")
+    fun internalSetLinks(value: List<Link>) {
+        links = links + value
+    }
+
+    @JsonSetter("name")
+    fun internalSetNames(value: List<Name>) {
+        names = names + value
+        names.forEach { if (it.type == "primary") name = it.value }
+    }
 }
 
 /** Available versions of the thing e.g. Different prints of a boardgame. */
+@Serializable
 data class Version(
     /** Type of version e.g. 'boardgameversion'. */
     @JacksonXmlProperty(isAttribute = true) val type: String,
@@ -237,7 +195,9 @@ data class Version(
     @JsonDeserialize(using = WrappedIntDeserializer::class) val yearPublished: Int?,
 
     /** The year it was released in e.g. `2019`. (For video games) */
-    @JsonDeserialize(using = WrappedLocalDateDeserializer::class) val releaseDate: LocalDate?,
+    @JsonDeserialize(using = WrappedLocalDateDeserializer::class)
+    @Serializable(with = LocalDateSerializer::class)
+    val releaseDate: LocalDate?,
 
     /** Product code of the product. */
     @JsonDeserialize(using = WrappedStringDeserializer::class) val productCode: String?,
@@ -253,30 +213,34 @@ data class Version(
 
     /** Weight in lbs (pounds). */
     @JsonDeserialize(using = WrappedDoubleDeserializer::class) val weight: Double?,
-) {
-    /** Names of the product, consisting of a primary and optionally alternatives. */
-    @JsonProperty("name")
-    var names: List<Name> = listOf()
-        set(value) {
-            field = field + value
-            field.forEach { if (it.type == "primary") name = it.value }
-        }
 
     /** Primary name. */
-    @JsonIgnore var name = ""
+    @JsonIgnore var name: String = "",
+
+    /** Names of the product, consisting of a primary and optionally alternatives. */
+    var names: List<Name> = listOf(),
+
+    /** Additional information about this product e.g. Language, artist(s) etc. */
+    var links: List<Link> = listOf(),
+) {
+    @JsonSetter("name")
+    fun internalSetNames(value: List<Name>) {
+        names = names + value
+        names.forEach { if (it.type == "primary") name = it.value }
+    }
 
     /** Additional information about this product e.g. Language, artist(s) etc. */
-    @JsonProperty("link")
-    var links: List<Link> = listOf()
-        set(value) {
-            field = field + value
-        }
+    @JsonSetter("link")
+    fun internalSetLinks(value: List<Link>) {
+        links = links + value
+    }
 }
 
 /**
  * Describes an associated video on the thing. In addition to a title and link the videos are also
  * categorized: `instructional`, `review` etc. and contain poster(user) information.
  */
+@Serializable
 data class Video(
     /** The unique ID to retrieve the video on BGG. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -311,6 +275,7 @@ data class Video(
     /** When the video was posted. */
     @JacksonXmlProperty(isAttribute = true)
     @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ssz")
+    @Serializable(with = LocalDateTimeSerializer::class)
     val postDate: LocalDateTime
 )
 
@@ -321,6 +286,7 @@ data class Video(
  *
  * @see org.audux.bgg.request.things
  */
+@Serializable
 data class Comments(
     /**
      * The current page of comments.
@@ -331,8 +297,8 @@ data class Comments(
 
     /**
      * Total number of comments for the specified type of comments, current items in this collection
-     * are specified by the request: [org.audux.bgg.request.Constants.PARAM_PAGE] and
-     * [org.audux.bgg.request.Constants.PARAM_PAGE_SIZE] which are passed in via the `page` and
+     * are specified by the request: [org.audux.bgg.common.Constants.PARAM_PAGE] and
+     * [org.audux.bgg.common.Constants.PARAM_PAGE_SIZE] which are passed in via the `page` and
      * `pageSize` parameters in [org.audux.bgg.request.things].
      */
     @JacksonXmlProperty(isAttribute = true) val totalItems: Int,
@@ -348,6 +314,7 @@ data class Comments(
  * Encapsulated both ratings and comments. Comments can have both [rating] and [value] set but which
  * one will always be set in the collection is specified in the request instead.
  */
+@Serializable
 data class Comment(
     /** Username of the user that posted the rating/comment. */
     @JacksonXmlProperty(isAttribute = true) val username: String,
@@ -365,9 +332,12 @@ data class Comment(
 
 // region Marketplace
 /** A single listing for the thing i.e. a 'for sale'-listing. */
+@Serializable
 data class MarketplaceListing(
     /** When the listing was created. */
-    @JsonDeserialize(using = WrappedLocalDateTimeDeserializer::class) val listDate: LocalDateTime,
+    @JsonDeserialize(using = WrappedLocalDateTimeDeserializer::class)
+    @Serializable(with = LocalDateTimeSerializer::class)
+    val listDate: LocalDateTime,
 
     /** The requested price for the listing. */
     val price: Price,
@@ -383,6 +353,7 @@ data class MarketplaceListing(
 )
 
 /** Encapsulates a price for a given [MarketplaceListing] */
+@Serializable
 data class Price(
     /** The actual price. */
     val value: Double,
@@ -392,9 +363,10 @@ data class Price(
 )
 
 /** Link to a web resource including a title/description. */
+@Serializable
 data class Weblink(
     /** Link to web resource. */
-    val href: URI,
+    @Serializable(with = URISerializer::class) val href: URI,
 
     /** The title of the resource. */
     val title: String,
@@ -416,9 +388,11 @@ data class Weblink(
     JsonSubTypes.Type(value = PlayerAgePoll::class, name = "suggested_playerage"),
     JsonSubTypes.Type(value = NumberOfPlayersPoll::class, name = "suggested_numplayers"),
 )
-interface Poll
+@Serializable(with = PollSerializer::class)
+sealed interface Poll
 
 /** Poll that contains the votes for the preferred number of players to engage with the thing. */
+@Serializable
 data class NumberOfPlayersPoll(
     /** English name/title of the poll e.g. "User Suggested Number of Players". */
     @JacksonXmlProperty(isAttribute = true) val title: String,
@@ -443,6 +417,7 @@ data class NumberOfPlayersPoll(
  *  </results>
  * ```
  */
+@Serializable
 data class NumberOfPlayersResults(
     /** The number of players these votes were cast for. */
     @JacksonXmlProperty(localName = "numplayers") val numberOfPlayers: String,
@@ -452,6 +427,7 @@ data class NumberOfPlayersResults(
 )
 
 /** Poll that contains the votes for the minimum age to engage with the thing. */
+@Serializable
 data class PlayerAgePoll(
     /** English name/title of the poll e.g. "User Suggested Player Age". */
     @JacksonXmlProperty(isAttribute = true) val title: String,
@@ -466,6 +442,7 @@ data class PlayerAgePoll(
 ) : Poll
 
 /** Poll that contains the votes for the minimum age to engage with the thing. */
+@Serializable
 data class LanguageDependencePoll(
     /** English name/title of the poll e.g. "Language Dependence". */
     @JacksonXmlProperty(isAttribute = true) val title: String,
@@ -480,6 +457,7 @@ data class LanguageDependencePoll(
 ) : Poll
 
 /** A single aggregate result i.e. votes for a single poll option. */
+@Serializable
 data class PollResult(
     /** The name/value of the poll option. */
     @JacksonXmlProperty(isAttribute = true) val value: String,
@@ -489,6 +467,7 @@ data class PollResult(
 )
 
 /** A single aggregate result i.e. votes for a single poll option including a level/gradation. */
+@Serializable
 data class LeveledPollResult(
     /** The name/value of the poll option. */
     @JacksonXmlProperty(isAttribute = true) val value: String,
diff --git a/src/main/kotlin/org/audux/bgg/response/Thread.kt b/src/main/kotlin/org/audux/bgg/response/Thread.kt
index b20cc7b..be86e52 100644
--- a/src/main/kotlin/org/audux/bgg/response/Thread.kt
+++ b/src/main/kotlin/org/audux/bgg/response/Thread.kt
@@ -19,9 +19,11 @@ import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDateTime
+import kotlinx.serialization.Serializable
 
 /** Encapsulates an entire thread and all of its articles/posts. */
 @JsonRootName("thread")
+@Serializable
 data class Thread(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -43,6 +45,7 @@ data class Thread(
 )
 
 /** Encapsulates an article in the current thread. */
+@Serializable
 data class Article(
     /** Unique ID that is used in the link below. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -61,11 +64,13 @@ data class Article(
     /** The date and time this article was created. */
     @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ssz")
     @JacksonXmlProperty(isAttribute = true)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val postDate: LocalDateTime?,
 
     /** The date and time a post was last edited. */
     @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ssz")
     @JacksonXmlProperty(isAttribute = true)
+    @Serializable(with = LocalDateTimeSerializer::class)
     val editDate: LocalDateTime?,
 
     /** Title/Subject of the article/post. */
diff --git a/src/main/kotlin/org/audux/bgg/response/User.kt b/src/main/kotlin/org/audux/bgg/response/User.kt
index 02f9468..5ed9431 100644
--- a/src/main/kotlin/org/audux/bgg/response/User.kt
+++ b/src/main/kotlin/org/audux/bgg/response/User.kt
@@ -18,12 +18,14 @@ import com.fasterxml.jackson.annotation.JsonRootName
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty
 import java.time.LocalDate
+import kotlinx.serialization.Serializable
 
 /**
  * Response wrapper for User response, contains user information and optionally lists of buddies,
  * guilds, top games and hot games.
  */
 @JsonRootName("user")
+@Serializable
 data class User(
     /** Terms of use of the BGG API. */
     @JacksonXmlProperty(isAttribute = true) val termsOfUse: String,
@@ -47,7 +49,9 @@ data class User(
     @JsonDeserialize(using = WrappedIntDeserializer::class) val yearRegistered: Int?,
 
     /** Date the user last logged in */
-    @JsonDeserialize(using = WrappedLocalDateDeserializer::class) val lastLogin: LocalDate?,
+    @JsonDeserialize(using = WrappedLocalDateDeserializer::class)
+    @Serializable(with = LocalDateSerializer::class)
+    val lastLogin: LocalDate?,
 
     /** The state or province the user lives - if provided. */
     @JsonDeserialize(using = WrappedStringDeserializer::class) val stateOrProvince: String?,
@@ -90,6 +94,7 @@ data class User(
 )
 
 /** List of Buddies/Friends of the user. */
+@Serializable
 data class Buddies(
     /** Total number of buddies. */
     val total: Int,
@@ -102,6 +107,7 @@ data class Buddies(
 )
 
 /** Buddy of the user. */
+@Serializable
 data class Buddy(
     /** The id of the buddy. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -111,6 +117,7 @@ data class Buddy(
 )
 
 /** Guilds user is a member of. */
+@Serializable
 data class Guilds(
     /** The total number of guilds user is a member of. */
     val total: Int,
@@ -123,6 +130,7 @@ data class Guilds(
 )
 
 /** The id and name of a guild the user is a member of. */
+@Serializable
 data class GuildReference(
     /** The id of the guild. */
     @JacksonXmlProperty(isAttribute = true) val id: Int,
@@ -132,6 +140,7 @@ data class GuildReference(
 )
 
 /** The list of Hot items the user has added to their 'hot list' - as seen on their profile. */
+@Serializable
 data class Hot(
     /** The domain the hot list was specified on i.e. 'boardgame' - same as in the request. */
     @JacksonXmlProperty(isAttribute = true) val domain: String,
@@ -141,6 +150,7 @@ data class Hot(
 )
 
 /** The list of Top items the user has added to their 'top list' - as seen on their profile. */
+@Serializable
 data class Top(
     /** The domain the top list was specified on i.e. 'boardgame' - same as in the request. */
     @JacksonXmlProperty(isAttribute = true) val domain: String,
@@ -153,6 +163,7 @@ data class Top(
  * Simple view of a item in the hot or top lists of the user, describing a boardgame, rpg etc. The
  * [org.audux.bgg.request.things] api may be used to request more information about the thing.
  */
+@Serializable
 data class ListItem(
     /** The (local) rank of the thin, i.e. the rank of the item in the user's hot or top list. */
     @JacksonXmlProperty(isAttribute = true) val rank: Int,
diff --git a/src/test/java/org/audux/bgg/BggClientJavaTest.java b/src/test/java/org/audux/bgg/BggClientJavaTest.java
index 854dc65..340a5f1 100644
--- a/src/test/java/org/audux/bgg/BggClientJavaTest.java
+++ b/src/test/java/org/audux/bgg/BggClientJavaTest.java
@@ -11,6 +11,8 @@
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeoutException;
 import org.audux.bgg.common.Domain;
@@ -344,15 +346,15 @@ public void geekListRequest() throws ExecutionException, InterruptedException, T
                     + " Rank games right after playing, add notes to remember specific"
                     + " things and thoughts, and keep your collection up to date! It"
                     + " only takes a couple of games not added to easily forget you even"
-                    + " have a game."));
-    var firstComment =
-        new GeekListComment(
+                    + " have a game.",
+                List.of()));
+
+    var firstComment = new GeekListComment(
             /* username= */ "TomandJonna",
             /* date= */ LocalDateTime.of(2024, 2, 7, 14, 47, 55),
             /* postDate= */ LocalDateTime.of(2024, 2, 7, 14, 47, 55),
             /* editDate= */ LocalDateTime.of(2024, 2, 7, 14, 47, 55),
             /* thumbs= */ 2);
-    firstComment.setValue("Thank you");
     assertThat(geekList.getComments().get(0)).isEqualTo(firstComment);
   }
 
diff --git a/src/test/kotlin/org/audux/bgg/response/CollectionResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/CollectionResponseTest.kt
index 6b3e368..4704ff6 100644
--- a/src/test/kotlin/org/audux/bgg/response/CollectionResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/CollectionResponseTest.kt
@@ -16,6 +16,9 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDateTime
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.common.Rank
 import org.audux.bgg.common.Ratings
 import org.audux.bgg.common.ThingType
@@ -34,6 +37,20 @@ class CollectionResponseTest {
         assertThat(results.items).hasSize(0)
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val collection =
+            mapper.readValue(
+                TestUtils.xml(
+                    "collection?username=novaeux&stats=1&subtype=boardgame&excludesubtype=boardgameexpansion"
+                ),
+                Collection::class.java
+            )
+        val encodedCollection = Json.encodeToString(collection)
+
+        assertThat(Json.decodeFromString<Collection>(encodedCollection)).isEqualTo(collection)
+    }
+
     @Test
     fun `Parses collection items`() {
         val results =
diff --git a/src/test/kotlin/org/audux/bgg/response/FamilyResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/FamilyResponseTest.kt
index cd5b5e4..2dc34c6 100644
--- a/src/test/kotlin/org/audux/bgg/response/FamilyResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/FamilyResponseTest.kt
@@ -15,6 +15,9 @@ package org.audux.bgg.response
 
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.common.FamilyType
 import org.audux.bgg.common.Link
 import org.audux.bgg.common.Name
@@ -32,6 +35,14 @@ class FamilyResponseTest {
         assertThat(results.items).hasSize(0)
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val family = mapper.readValue(TestUtils.xml("family"), Family::class.java)
+        val encodedFamily = Json.encodeToString(family)
+
+        assertThat(Json.decodeFromString<Family>(encodedFamily)).isEqualTo(family)
+    }
+
     @Test
     fun `Parses a family with it's associated links`() {
         val results = mapper.readValue(TestUtils.xml("family"), Family::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/ForumListResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/ForumListResponseTest.kt
index a2b229f..abdc12f 100644
--- a/src/test/kotlin/org/audux/bgg/response/ForumListResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/ForumListResponseTest.kt
@@ -17,6 +17,9 @@ import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
 
@@ -31,6 +34,14 @@ class ForumListResponseTest {
         assertThat(results.forums).hasSize(0)
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val forumList = mapper.readValue(TestUtils.xml("forumlist"), ForumList::class.java)
+        val encodedForumList = Json.encodeToString(forumList)
+
+        assertThat(Json.decodeFromString<ForumList>(encodedForumList)).isEqualTo(forumList)
+    }
+
     @Test
     fun `Parses a Forum list for the given thing`() {
         val results = mapper.readValue(TestUtils.xml("forumlist"), ForumList::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/ForumResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/ForumResponseTest.kt
index bb17307..da2cd9d 100644
--- a/src/test/kotlin/org/audux/bgg/response/ForumResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/ForumResponseTest.kt
@@ -17,6 +17,9 @@ import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
@@ -35,6 +38,14 @@ class ForumResponseTest {
         assertThat(exception).hasMessageThat().contains("Unexpected character")
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val forum = mapper.readValue(TestUtils.xml("forum?id=3696796"), Forum::class.java)
+        val encodedForum = Json.encodeToString(forum)
+
+        assertThat(Json.decodeFromString<Forum>(encodedForum)).isEqualTo(forum)
+    }
+
     @Test
     fun `Parses the forum for the given thing`() {
         val results = mapper.readValue(TestUtils.xml("forum?id=3696796"), Forum::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/GeekListResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/GeekListResponseTest.kt
index 150b972..644fbb8 100644
--- a/src/test/kotlin/org/audux/bgg/response/GeekListResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/GeekListResponseTest.kt
@@ -16,6 +16,9 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDateTime
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.common.SubType
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
@@ -32,6 +35,15 @@ class GeekListResponseTest {
         }
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val geekList =
+            mapper.readValue(TestUtils.xml("geeklist?id=331520&comments=1"), GeekList::class.java)
+        val encodedGeekList = Json.encodeToString(geekList)
+
+        assertThat(Json.decodeFromString<GeekList>(encodedGeekList)).isEqualTo(geekList)
+    }
+
     @Test
     fun `Parses a Geek list`() {
         val results = mapper.readValue(TestUtils.xml("geeklist?id=331520"), GeekList::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/GuildResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/GuildResponseTest.kt
index 9a4abae..79b6f43 100644
--- a/src/test/kotlin/org/audux/bgg/response/GuildResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/GuildResponseTest.kt
@@ -16,6 +16,9 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDateTime
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
 
@@ -48,6 +51,15 @@ class GuildResponseTest {
             )
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val guild =
+            mapper.readValue(TestUtils.xml("guilds?id=2310&members=1&page=1"), Guild::class.java)
+        val encodedGuild = Json.encodeToString(guild)
+
+        assertThat(Json.decodeFromString<Guild>(encodedGuild)).isEqualTo(guild)
+    }
+
     @Test
     fun `Parses a guild including members`() {
         val results =
diff --git a/src/test/kotlin/org/audux/bgg/response/HotResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/HotResponseTest.kt
index 07e59bc..07ff313 100644
--- a/src/test/kotlin/org/audux/bgg/response/HotResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/HotResponseTest.kt
@@ -15,6 +15,9 @@ package org.audux.bgg.response
 
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
 
@@ -29,6 +32,14 @@ class HotResponseTest {
         assertThat(results.results).hasSize(0)
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val hotList = mapper.readValue(TestUtils.xml("hot"), HotList::class.java)
+        val encodedHotList = Json.encodeToString(hotList)
+
+        assertThat(Json.decodeFromString<HotList>(encodedHotList)).isEqualTo(hotList)
+    }
+
     @Test
     fun `Parses a hot list`() {
         val results = mapper.readValue(TestUtils.xml("hot"), HotList::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/PlaysResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/PlaysResponseTest.kt
index ce8626f..ca6191f 100644
--- a/src/test/kotlin/org/audux/bgg/response/PlaysResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/PlaysResponseTest.kt
@@ -16,6 +16,9 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDate
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.common.PlayThingType
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
@@ -32,6 +35,14 @@ class PlaysResponseTest {
         assertThat(results.plays).isEmpty()
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val plays = mapper.readValue(TestUtils.xml("plays?username=Novaeux"), Plays::class.java)
+        val encodedPlays = Json.encodeToString(plays)
+
+        assertThat(Json.decodeFromString<Plays>(encodedPlays)).isEqualTo(plays)
+    }
+
     @Test
     fun `Parses a list of plays`() {
         val results = mapper.readValue(TestUtils.xml("plays?username=Novaeux"), Plays::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/SearchResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/SearchResponseTest.kt
index 07da752..2e0bd6c 100644
--- a/src/test/kotlin/org/audux/bgg/response/SearchResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/SearchResponseTest.kt
@@ -15,6 +15,9 @@ package org.audux.bgg.response
 
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.common.Name
 import org.audux.bgg.common.ThingType
 import org.audux.bgg.util.TestUtils
@@ -33,6 +36,16 @@ class SearchResponseTest {
         assertThat(results.results).hasSize(0)
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val searchResults =
+            mapper.readValue(TestUtils.xml("search?query=my+little"), SearchResults::class.java)
+        val encodedSearchResults = Json.encodeToString(searchResults)
+
+        assertThat(Json.decodeFromString<SearchResults>(encodedSearchResults))
+            .isEqualTo(searchResults)
+    }
+
     @Test
     fun `Parses search results`() {
         val results =
diff --git a/src/test/kotlin/org/audux/bgg/response/SitemapIndexResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/SitemapIndexResponseTest.kt
index 8b170af..f7a8c1e 100644
--- a/src/test/kotlin/org/audux/bgg/response/SitemapIndexResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/SitemapIndexResponseTest.kt
@@ -15,6 +15,9 @@ package org.audux.bgg.response
 
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
 
@@ -22,6 +25,14 @@ import org.junit.jupiter.api.Test
 class SitemapIndexResponseTest {
     private val mapper: ObjectMapper = TestUtils.getBggClientMapper()
 
+    @Test
+    fun `is (K)Serializable`() {
+        val sitemapIndex = mapper.readValue(TestUtils.xml("sitemapindex"), SitemapIndex::class.java)
+        val encodedSitemapIndex = Json.encodeToString(sitemapIndex)
+
+        assertThat(Json.decodeFromString<SitemapIndex>(encodedSitemapIndex)).isEqualTo(sitemapIndex)
+    }
+
     @Test
     fun `Parses a Sitemap Index`() {
         val results = mapper.readValue(TestUtils.xml("sitemapindex"), SitemapIndex::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/SitemapResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/SitemapResponseTest.kt
index 029aa6c..6a82587 100644
--- a/src/test/kotlin/org/audux/bgg/response/SitemapResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/SitemapResponseTest.kt
@@ -15,6 +15,9 @@ package org.audux.bgg.response
 
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
 
@@ -22,6 +25,15 @@ import org.junit.jupiter.api.Test
 class SitemapResponseTest {
     private val mapper: ObjectMapper = TestUtils.getBggClientMapper()
 
+    @Test
+    fun `is (K)Serializable`() {
+        val sitemap =
+            mapper.readValue(TestUtils.xml("sitemap_boardgame_page1"), Sitemap::class.java)
+        val encodedSitemap = Json.encodeToString(sitemap)
+
+        assertThat(Json.decodeFromString<Sitemap>(encodedSitemap)).isEqualTo(sitemap)
+    }
+
     @Test
     fun `Parses a Sitemap`() {
         val results =
diff --git a/src/test/kotlin/org/audux/bgg/response/ThingsResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/ThingsResponseTest.kt
index afd824e..b555bef 100644
--- a/src/test/kotlin/org/audux/bgg/response/ThingsResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/ThingsResponseTest.kt
@@ -18,6 +18,9 @@ import com.google.common.truth.Truth.assertThat
 import java.net.URI
 import java.time.LocalDate
 import java.time.LocalDateTime
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.common.ThingType
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Nested
@@ -41,6 +44,21 @@ class ThingsResponseTest {
         assertThat(things.things).hasSize(3)
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val things =
+            mapper.readValue(
+                TestUtils.xml(
+                    "thing?id=396790&stats=1&ratingcomments=1&versions=1&marketplace=1&videos=1"
+                ),
+                Things::class.java
+            )
+        val thing = things.things[0]
+        val encodedThing = Json.encodeToString(thing)
+
+        assertThat(Json.decodeFromString<Thing>(encodedThing)).isEqualTo(thing)
+    }
+
     @Nested
     inner class BoardGame {
         @Test
diff --git a/src/test/kotlin/org/audux/bgg/response/ThreadResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/ThreadResponseTest.kt
index a300111..cc68230 100644
--- a/src/test/kotlin/org/audux/bgg/response/ThreadResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/ThreadResponseTest.kt
@@ -17,6 +17,9 @@ import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
@@ -32,6 +35,14 @@ class ThreadResponseTest {
         }
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val thread = mapper.readValue(TestUtils.xml("thread"), Thread::class.java)
+        val encodedThread = Json.encodeToString(thread)
+
+        assertThat(Json.decodeFromString<Thread>(encodedThread)).isEqualTo(thread)
+    }
+
     @Test
     fun `Parses the thread for the given thing`() {
         val thread = mapper.readValue(TestUtils.xml("thread"), Thread::class.java)
diff --git a/src/test/kotlin/org/audux/bgg/response/UserResponseTest.kt b/src/test/kotlin/org/audux/bgg/response/UserResponseTest.kt
index 8762819..edb739f 100644
--- a/src/test/kotlin/org/audux/bgg/response/UserResponseTest.kt
+++ b/src/test/kotlin/org/audux/bgg/response/UserResponseTest.kt
@@ -16,6 +16,9 @@ package org.audux.bgg.response
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.truth.Truth.assertThat
 import java.time.LocalDate
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.audux.bgg.util.TestUtils
 import org.audux.bgg.util.TestUtils.xml
 import org.junit.jupiter.api.Test
@@ -31,6 +34,18 @@ class UserResponseTest {
         assertThat(results.name).isEmpty()
     }
 
+    @Test
+    fun `is (K)Serializable`() {
+        val user =
+            mapper.readValue(
+                xml("user?name=Novaeux&buddies=1&hot=1&top=1&guilds=1&page=1&domain=boardgame"),
+                User::class.java
+            )
+        val encodedUser = Json.encodeToString(user)
+
+        assertThat(Json.decodeFromString<User>(encodedUser)).isEqualTo(user)
+    }
+
     @Test
     fun `Parses a user without extras`() {
         val results = mapper.readValue(xml("user?name=Novaeux"), User::class.java)