diff --git a/backend/build.gradle b/backend/build.gradle
index 721ed675a..03b4e0800 100644
--- a/backend/build.gradle
+++ b/backend/build.gradle
@@ -113,6 +113,7 @@ dependencies {
     ///// Kotlin
     implementation group: 'org.jetbrains.kotlin', name: 'kotlin-stdlib', version: version_kotlin
     implementation group: 'org.jetbrains.kotlin', name: 'kotlin-reflect', version: version_kotlin
+    implementation group: 'org.jetbrains.kotlinx', name:'kotlinx-serialization-json', version: '1.6.2'
 }
 
 kapt {
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/KotlinxJsonMapper.kt b/backend/src/main/kotlin/dev/dres/api/rest/KotlinxJsonMapper.kt
new file mode 100644
index 000000000..628f23c3d
--- /dev/null
+++ b/backend/src/main/kotlin/dev/dres/api/rest/KotlinxJsonMapper.kt
@@ -0,0 +1,42 @@
+package dev.dres.api.rest
+
+import com.fasterxml.jackson.core.type.TypeReference
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import io.javalin.json.JsonMapper
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.SerializationException
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.serializer
+import java.lang.reflect.Type
+
+object KotlinxJsonMapper : JsonMapper {
+
+    private val fallbackMapper = jacksonObjectMapper()
+
+    override fun <T : Any> fromJsonString(json: String, targetType: Type): T {
+
+        return try {
+            @Suppress("UNCHECKED_CAST")
+            val serializer = serializer(targetType) as KSerializer<T>
+            Json.decodeFromString(serializer, json)
+        } catch (e: SerializationException) {
+            null
+        } catch (e: IllegalStateException) {
+            null
+        } ?: fallbackMapper.readValue(json, fallbackMapper.typeFactory.constructType(targetType))
+
+    }
+
+    override fun toJsonString(obj: Any, type: Type): String {
+
+        return try {
+            val serializer = serializer(type)
+            Json.encodeToString(serializer, obj)
+        } catch (e: SerializationException) {
+            null
+        } catch (e: IllegalStateException) {
+            null
+        } ?: fallbackMapper.writeValueAsString(obj)
+
+    }
+}
\ No newline at end of file
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/RestApi.kt b/backend/src/main/kotlin/dev/dres/api/rest/RestApi.kt
index 9d1de820f..b14d85bcf 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/RestApi.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/RestApi.kt
@@ -226,6 +226,9 @@ object RestApi {
         )
 
         javalin = Javalin.create {
+
+            it.jsonMapper(KotlinxJsonMapper)
+
             it.plugins.enableCors { cors ->
                 cors.add { corsPluginConfig ->
                     corsPluginConfig.reflectClientOrigin =
@@ -381,8 +384,8 @@ object RestApi {
 
 
     private val pool = QueuedThreadPool(
-        min(Runtime.getRuntime().availableProcessors() * 2, 8),
-        8,
+        32,
+        10,
         60000,
         -1,
         null,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/handler/system/LoginHandler.kt b/backend/src/main/kotlin/dev/dres/api/rest/handler/system/LoginHandler.kt
index 9678086ce..63764678c 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/handler/system/LoginHandler.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/handler/system/LoginHandler.kt
@@ -16,6 +16,7 @@ import io.javalin.http.BadRequestResponse
 import io.javalin.http.Context
 import io.javalin.openapi.*
 import jetbrains.exodus.database.TransientEntityStore
+import kotlinx.serialization.Serializable
 
 /**
  * A [PostRestHandler] that handles user-requests to login.
@@ -28,6 +29,7 @@ class LoginHandler() : RestHandler, PostRestHandler<ApiUser> {
     override val route = "login"
     override val apiVersion = RestApi.LATEST_API_VERSION
 
+    @Serializable
     data class LoginRequest(var username: String, var password: String)
 
     @OpenApi(
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItem.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItem.kt
index 73de65f91..73162a701 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItem.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItem.kt
@@ -5,6 +5,7 @@ import dev.dres.data.model.media.*
 import kotlinx.dnq.query.filter
 import kotlinx.dnq.query.first
 import kotlinx.dnq.util.findById
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent for [DbMediaItem].
@@ -13,6 +14,7 @@ import kotlinx.dnq.util.findById
  * @author Ralph Gasser
  * @version 1.1.0
  */
+@Serializable
 data class ApiMediaItem(
     override val mediaItemId: MediaItemId,
     override val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItemMetaDataEntry.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItemMetaDataEntry.kt
index 568ea37fe..2f643ae82 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItemMetaDataEntry.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/ApiMediaItemMetaDataEntry.kt
@@ -1,3 +1,6 @@
 package dev.dres.api.rest.types.collection
 
+import kotlinx.serialization.Serializable
+
+@Serializable
 data class ApiMediaItemMetaDataEntry(val key: String, val value: String)
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalPoint.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalPoint.kt
index 9dd6aea19..06957e2da 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalPoint.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalPoint.kt
@@ -1,6 +1,7 @@
 package dev.dres.api.rest.types.collection.time
 
 import dev.dres.data.model.media.time.TemporalPoint
+import kotlinx.serialization.Serializable
 
 /**
  * RESTful API representation of a [TemporalPoint].
@@ -8,6 +9,7 @@ import dev.dres.data.model.media.time.TemporalPoint
  * @version 1.0.0
  * @author Ralph Gasser
  */
+@Serializable
 data class ApiTemporalPoint(val value: String, val unit: ApiTemporalUnit) {
 
     companion object{
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalRange.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalRange.kt
index cf6c4e35d..b6e818eb1 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalRange.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/collection/time/ApiTemporalRange.kt
@@ -1,6 +1,7 @@
 package dev.dres.api.rest.types.collection.time
 
 import dev.dres.data.model.media.time.TemporalRange
+import kotlinx.serialization.Serializable
 
 /**
  * RESTful API representation of a [TemporalRange].
@@ -8,6 +9,7 @@ import dev.dres.data.model.media.time.TemporalRange
  * @version 1.0.0
  * @author Ralph Gasser
  */
+@Serializable
 data class ApiTemporalRange(val start: ApiTemporalPoint, val end: ApiTemporalPoint) {
     constructor(range: TemporalRange) : this(ApiTemporalPoint.fromTemporalPoint(range.start), ApiTemporalPoint.fromTemporalPoint(range.end))
     fun toTemporalRange(fps: Float): TemporalRange = TemporalRange(start.toTemporalPoint(fps), end.toTemporalPoint(fps))
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientEvaluationInfo.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientEvaluationInfo.kt
index 4426b343b..8ccaf196d 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientEvaluationInfo.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientEvaluationInfo.kt
@@ -5,11 +5,13 @@ import dev.dres.run.InteractiveAsynchronousRunManager
 import dev.dres.run.InteractiveSynchronousRunManager
 import dev.dres.run.NonInteractiveRunManager
 import dev.dres.run.RunManager
+import kotlinx.serialization.Serializable
 
 /**
  * Contains the basic and most importantly static information about a [RunManager] that is relevant to a participant.
  *
  */
+@Serializable
 data class ApiClientEvaluationInfo(
     val id: String,
     val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientTaskTemplateInfo.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientTaskTemplateInfo.kt
index 7a042a686..b03b3680b 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientTaskTemplateInfo.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiClientTaskTemplateInfo.kt
@@ -2,10 +2,12 @@ package dev.dres.api.rest.types.evaluation
 
 import dev.dres.api.rest.types.template.tasks.ApiTaskTemplate
 import dev.dres.data.model.template.task.DbTaskTemplate
+import kotlinx.serialization.Serializable
 
 /**
  * Basic and most importantly static information about a [DbTaskTemplate] relevant to the participant.
  */
+@Serializable
 data class ApiClientTaskTemplateInfo(
     val name: String,
     val taskGroup: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluation.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluation.kt
index 358efc606..377136ca3 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluation.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluation.kt
@@ -4,6 +4,7 @@ import dev.dres.api.rest.types.template.ApiEvaluationTemplate
 import dev.dres.data.model.run.DbEvaluation
 import dev.dres.data.model.run.interfaces.Evaluation
 import dev.dres.data.model.run.interfaces.EvaluationId
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent of a [DbEvaluation].
@@ -12,6 +13,7 @@ import dev.dres.data.model.run.interfaces.EvaluationId
  * @author Ralph Gasser
  * @version 2.0.0
  */
+@Serializable
 data class ApiEvaluation(
     override val evaluationId: EvaluationId,
     val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationInfo.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationInfo.kt
index a250552ba..18833e56a 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationInfo.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationInfo.kt
@@ -5,6 +5,7 @@ import dev.dres.run.InteractiveAsynchronousRunManager
 import dev.dres.run.InteractiveSynchronousRunManager
 import dev.dres.run.NonInteractiveRunManager
 import dev.dres.run.RunManager
+import kotlinx.serialization.Serializable
 
 /**
  * Contains the basic and most importantly static information about a [RunManager].
@@ -14,6 +15,7 @@ import dev.dres.run.RunManager
  * @author Ralph Gasser
  * @version 1.1.0
  */
+@Serializable
 data class ApiEvaluationInfo(
     val id: String,
     val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationOverview.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationOverview.kt
index cb93b299f..1c0ffbf66 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationOverview.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationOverview.kt
@@ -1,7 +1,9 @@
 package dev.dres.api.rest.types.evaluation
 
 import dev.dres.run.*
+import kotlinx.serialization.Serializable
 
+@Serializable
 data class ApiEvaluationOverview(val state: RunManagerStatus, val teamOverviews: List<ApiTeamTaskOverview>) {
     companion object {
         fun of(manager: InteractiveRunManager): ApiEvaluationOverview {
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationState.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationState.kt
index 89c9f3a7a..bda41113c 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationState.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiEvaluationState.kt
@@ -2,6 +2,7 @@ package dev.dres.api.rest.types.evaluation
 
 import dev.dres.data.model.run.RunActionContext
 import dev.dres.run.*
+import kotlinx.serialization.Serializable
 
 /**
  * Contains the information about the state of an [InteractiveRunManager].
@@ -10,6 +11,7 @@ import dev.dres.run.*
  *
  * @version 1.3.0
  */
+@Serializable
 data class ApiEvaluationState(
     val evaluationId: String,
     val evaluationStatus: ApiEvaluationStatus,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiOverrideAnswerSetVerdictDto.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiOverrideAnswerSetVerdictDto.kt
index a0b7e0c45..e8d1eca42 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiOverrideAnswerSetVerdictDto.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiOverrideAnswerSetVerdictDto.kt
@@ -1,6 +1,7 @@
 package dev.dres.api.rest.types.evaluation
 
 import dev.dres.api.rest.types.evaluation.submission.ApiVerdictStatus
+import kotlinx.serialization.Serializable
 
 /**
  * Data transfer object for overriding a [ApiAnswerSet]'s verdict.
@@ -9,4 +10,5 @@ import dev.dres.api.rest.types.evaluation.submission.ApiVerdictStatus
  * @author Loris Sauter
  * @version 1.0
  */
+@Serializable
 data class ApiOverrideAnswerSetVerdictDto(val verdict: ApiVerdictStatus)
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiSubmissionInfo.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiSubmissionInfo.kt
index 6a1c80558..feecea5e5 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiSubmissionInfo.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiSubmissionInfo.kt
@@ -3,6 +3,7 @@ package dev.dres.api.rest.types.evaluation
 import dev.dres.api.rest.types.evaluation.submission.ApiSubmission
 import dev.dres.data.model.run.interfaces.EvaluationId
 import dev.dres.data.model.template.TemplateId
+import kotlinx.serialization.Serializable
 
 /**
  * Encodes [ApiSubmission] data for a specific [EvaluationId] and (optionally) [EvaluationId].
@@ -10,4 +11,5 @@ import dev.dres.data.model.template.TemplateId
  * @author Loris Sauter
  * @version 1.1.0
  */
+@Serializable
 data class ApiSubmissionInfo(val evaluationId: EvaluationId, val taskId: TemplateId, val submissions: List<ApiSubmission>)
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTask.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTask.kt
index 6f6e7603f..031a98888 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTask.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTask.kt
@@ -4,6 +4,7 @@ import dev.dres.api.rest.types.evaluation.submission.ApiAnswerSet
 import dev.dres.data.model.run.DbTask
 import dev.dres.data.model.run.TaskId
 import dev.dres.data.model.template.TemplateId
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent of a [DbTask].
@@ -12,6 +13,7 @@ import dev.dres.data.model.template.TemplateId
  * @author Ralph Gasser
  * @version 2.0.0
  */
+@Serializable
 data class ApiTask(
     val taskId: TaskId,
     val templateId: TemplateId,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskOverview.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskOverview.kt
index d5a7db493..0099f8ce8 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskOverview.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskOverview.kt
@@ -1,7 +1,9 @@
 package dev.dres.api.rest.types.evaluation
 
 import dev.dres.data.model.run.interfaces.TaskRun
+import kotlinx.serialization.Serializable
 
+@Serializable
 data class ApiTaskOverview(
     val id: String,
     val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskTemplateInfo.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskTemplateInfo.kt
index 76c14a88b..11aa5f2ad 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskTemplateInfo.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTaskTemplateInfo.kt
@@ -2,6 +2,7 @@ package dev.dres.api.rest.types.evaluation
 
 import dev.dres.api.rest.types.template.tasks.ApiTaskTemplate
 import dev.dres.data.model.template.task.DbTaskTemplate
+import kotlinx.serialization.Serializable
 
 /**
  * Basic and most importantly static information about a [DbTaskTemplate].
@@ -11,6 +12,7 @@ import dev.dres.data.model.template.task.DbTaskTemplate
  * @author Ralph Gasser & Loris Sauter
  * @version 1.2.0
  */
+@Serializable
 data class ApiTaskTemplateInfo(
     val templateId: String,
     val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamInfo.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamInfo.kt
index f5205c964..a45746ffb 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamInfo.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamInfo.kt
@@ -4,6 +4,7 @@ import dev.dres.api.rest.types.template.team.ApiTeam
 import dev.dres.data.model.template.team.DbTeam
 import dev.dres.data.model.run.InteractiveSynchronousEvaluation
 import dev.dres.data.model.template.team.TeamId
+import kotlinx.serialization.Serializable
 
 /**
  * Basic and most importantly static information about the [DbTeam] partaking in a [InteractiveSynchronousEvaluation].
@@ -13,6 +14,8 @@ import dev.dres.data.model.template.team.TeamId
  * @author Ralph Gasser
  * @version 1.1.0
  */
+
+@Serializable
 data class ApiTeamInfo(val id: TeamId, val name: String, val color: String) {
     constructor(team: ApiTeam) : this(team.id!!, team.name!!, team.color!!)
 }
\ No newline at end of file
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamTaskOverview.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamTaskOverview.kt
index 755bc4f85..8cdcc67ea 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamTaskOverview.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiTeamTaskOverview.kt
@@ -1,3 +1,6 @@
 package dev.dres.api.rest.types.evaluation
 
+import kotlinx.serialization.Serializable
+
+@Serializable
 data class ApiTeamTaskOverview(val teamId: String, val tasks: List<ApiTaskOverview>)
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiViewerInfo.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiViewerInfo.kt
index aa2be6e61..1740639a4 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiViewerInfo.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/ApiViewerInfo.kt
@@ -1,9 +1,12 @@
 package dev.dres.api.rest.types.evaluation
 
+import kotlinx.serialization.Serializable
+
 /**
  * Basic information regarding a viewer instance
  *
  * @author Ralph Gasser
  * @version 1.1.0
  */
+@Serializable
 data class ApiViewerInfo(val viewersId: String, val username: String, val host: String, val ready: Boolean)
\ No newline at end of file
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswer.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswer.kt
index d2078dac4..88de48504 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswer.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswer.kt
@@ -3,6 +3,7 @@ package dev.dres.api.rest.types.evaluation.submission
 import dev.dres.api.rest.types.collection.ApiMediaItem
 import dev.dres.data.model.submissions.Answer
 import dev.dres.data.model.submissions.AnswerType
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent for the type of answer as submitted by the DRES endpoint.
@@ -13,6 +14,7 @@ import dev.dres.data.model.submissions.AnswerType
  * @author Ralph Gasser
  * @version 1.0.0
  */
+@Serializable
 data class ApiAnswer(
     /** The [ApiAnswerType] of this [ApiAnswer]. */
     val type: ApiAnswerType,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswerSet.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswerSet.kt
index 3ac0977a4..9c0324d78 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswerSet.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiAnswerSet.kt
@@ -4,6 +4,7 @@ import com.fasterxml.jackson.annotation.JsonIgnore
 import dev.dres.data.model.run.TaskId
 import dev.dres.data.model.submissions.*
 import io.javalin.openapi.OpenApiIgnore
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent for the type of answer set as submitted by the DRES endpoint.
@@ -14,6 +15,7 @@ import io.javalin.openapi.OpenApiIgnore
  * @author Ralph Gasser
  * @version 1.0.0
  */
+@Serializable
 data class ApiAnswerSet(
     override val id: AnswerSetId,
     val status: ApiVerdictStatus,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswer.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswer.kt
index e4a2a8ae1..d746c8402 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswer.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswer.kt
@@ -8,6 +8,7 @@ import dev.dres.data.model.submissions.DbAnswerType
 import io.javalin.openapi.OpenApiIgnore
 import kotlinx.dnq.query.filter
 import kotlinx.dnq.query.singleOrNull
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent of an answer as provided by a client of the submission API endpoints.
@@ -17,7 +18,8 @@ import kotlinx.dnq.query.singleOrNull
  * @author Luca Rossetto
  * @version 1.0.0
  */
-data class ApiClientAnswer(
+@Serializable
+data class ApiClientAnswer( //TODO add optional relevance score field
     /** The text that is part of this [ApiClientAnswer]. */
     val text: String? = null,
 
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswerSet.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswerSet.kt
index 8210ddb97..b91149b61 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswerSet.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientAnswerSet.kt
@@ -9,6 +9,7 @@ import io.javalin.openapi.OpenApiIgnore
 import kotlinx.dnq.query.addAll
 import kotlinx.dnq.query.filter
 import kotlinx.dnq.query.first
+import kotlinx.serialization.Serializable
 import java.util.*
 
 /**
@@ -19,6 +20,7 @@ import java.util.*
  * @author Luca Rossetto
  * @version 1.0.0
  */
+@Serializable
 data class ApiClientAnswerSet(var taskId: String? = null, val taskName: String? = null, val answers: List<ApiClientAnswer>) {
 
     /** The [AnswerSetId] of this [ApiClientAnswerSet]. Typically generated by the receiving endpoint. */
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientSubmission.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientSubmission.kt
index 50488ec40..0b2ab1bba 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientSubmission.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiClientSubmission.kt
@@ -13,6 +13,7 @@ import kotlinx.dnq.query.addAll
 import kotlinx.dnq.query.filter
 import kotlinx.dnq.query.single
 import kotlinx.dnq.query.singleOrNull
+import kotlinx.serialization.Serializable
 import java.util.UUID
 
 /**
@@ -23,6 +24,7 @@ import java.util.UUID
  * @author Luca Rossetto
  * @version 1.0.0
  */
+@Serializable
 data class ApiClientSubmission(
     val answerSets: List<ApiClientAnswerSet>,
     /** The [UserId] associated with the submission. Is usually added as contextual information by the receiving endpoint. */
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiSubmission.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiSubmission.kt
index 90a6011ef..5cd3c1dd3 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiSubmission.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/evaluation/submission/ApiSubmission.kt
@@ -2,6 +2,7 @@ package dev.dres.api.rest.types.evaluation.submission
 
 
 import dev.dres.data.model.submissions.*
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent of a submission as returned by the DRES endpoint.
@@ -12,6 +13,7 @@ import dev.dres.data.model.submissions.*
  * @author Ralph Gasser
  * @version 2.0.0
  */
+@Serializable
 data class ApiSubmission(
     override val submissionId: SubmissionId,
     override val teamId: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/status/AbstractStatus.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/status/AbstractStatus.kt
index 50fedbebe..55abeef1c 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/status/AbstractStatus.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/status/AbstractStatus.kt
@@ -1,3 +1,6 @@
 package dev.dres.api.rest.types.status
 
+import kotlinx.serialization.Serializable
+
+@Serializable
 open class AbstractStatus(val status:Boolean){}
\ No newline at end of file
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatus.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatus.kt
index 2b0d79813..e6989a892 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatus.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatus.kt
@@ -1,3 +1,6 @@
 package dev.dres.api.rest.types.status
 
+import kotlinx.serialization.Serializable
+
+@Serializable
 data class ErrorStatus(val description: String): AbstractStatus(status = false)
\ No newline at end of file
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatusException.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatusException.kt
index 0e2a84f64..986a851b4 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatusException.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/status/ErrorStatusException.kt
@@ -1,8 +1,10 @@
 package dev.dres.api.rest.types.status
 
 import io.javalin.http.Context
+import kotlinx.serialization.Serializable
 import org.slf4j.LoggerFactory
 
+@Serializable
 data class ErrorStatusException(val statusCode: Int, val status: String, private val ctx: Context, val doNotLog: Boolean = false) : Exception(status) {
     companion object {
         private val logger = LoggerFactory.getLogger(this::class.java)
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessStatus.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessStatus.kt
index 62c4da38c..00b82be11 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessStatus.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessStatus.kt
@@ -1,3 +1,6 @@
 package dev.dres.api.rest.types.status
 
+import kotlinx.serialization.Serializable
+
+@Serializable
 data class SuccessStatus(val description: String): AbstractStatus(status = true)
\ No newline at end of file
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessfulSubmissionsStatus.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessfulSubmissionsStatus.kt
index ac78a7a21..62c74310b 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessfulSubmissionsStatus.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/status/SuccessfulSubmissionsStatus.kt
@@ -1,5 +1,7 @@
 package dev.dres.api.rest.types.status
 
 import dev.dres.api.rest.types.evaluation.submission.ApiVerdictStatus
+import kotlinx.serialization.Serializable
 
+@Serializable
 data class SuccessfulSubmissionsStatus(val submission: ApiVerdictStatus, val description: String) : AbstractStatus(status = true)
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/ApiEvaluationTemplate.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/ApiEvaluationTemplate.kt
index a9dd482e8..951bf1285 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/ApiEvaluationTemplate.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/ApiEvaluationTemplate.kt
@@ -10,6 +10,7 @@ import dev.dres.data.model.admin.UserId
 import dev.dres.data.model.template.DbEvaluationTemplate
 import dev.dres.data.model.template.TemplateId
 import io.javalin.openapi.OpenApiIgnore
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent for [DbEvaluationTemplate].
@@ -18,6 +19,7 @@ import io.javalin.openapi.OpenApiIgnore
  * @author Luca Rossetto & Ralph Gasser
  * @version 2.0.0
  */
+@Serializable
 data class ApiEvaluationTemplate(
     val id: TemplateId,
     val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiHint.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiHint.kt
index 519e2a415..4d95f38d5 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiHint.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiHint.kt
@@ -2,6 +2,7 @@ package dev.dres.api.rest.types.template.tasks
 
 import dev.dres.api.rest.types.collection.time.ApiTemporalRange
 import dev.dres.data.model.template.*
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent for [TaskDescriptionHint].
@@ -9,6 +10,7 @@ import dev.dres.data.model.template.*
  * @author Luca Rossetto & Ralph Gasser & Loris Sauter
  * @version 2.1.0
  */
+@Serializable
 data class ApiHint(
         /**
          * The type of this component
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTarget.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTarget.kt
index 88c4dd478..4769ab6d7 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTarget.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTarget.kt
@@ -2,6 +2,7 @@ package dev.dres.api.rest.types.template.tasks
 
 import dev.dres.api.rest.types.collection.time.ApiTemporalRange
 import dev.dres.data.model.template.task.DbTaskTemplateTarget
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent for [DbTaskTemplateTarget].
@@ -9,6 +10,7 @@ import dev.dres.data.model.template.task.DbTaskTemplateTarget
  * @author Luca Rossetto & Ralph Gasser & Loris Sauter
  * @version 1.1.0
  */
+@Serializable
 data class ApiTarget(
     val type: ApiTargetType,
     /**
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskGroup.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskGroup.kt
index 5711b842a..8c4faf3f4 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskGroup.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskGroup.kt
@@ -1,6 +1,7 @@
 package dev.dres.api.rest.types.template.tasks
 
 import dev.dres.data.model.template.task.DbTaskGroup
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent of a [DbTaskGroup].
@@ -8,4 +9,5 @@ import dev.dres.data.model.template.task.DbTaskGroup
  * @author Ralph Gasser
  * @version 1.0.0
  */
+@Serializable
 data class ApiTaskGroup(val id: String?,val name: String, val type: String)
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskTemplate.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskTemplate.kt
index 10cee7691..bcf61c0d5 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskTemplate.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskTemplate.kt
@@ -8,6 +8,7 @@ import dev.dres.data.model.template.TemplateId
 import dev.dres.data.model.template.task.TaskTemplate
 import dev.dres.data.model.template.task.TaskTemplateId
 import io.javalin.openapi.OpenApiIgnore
+import kotlinx.serialization.Serializable
 
 /**
  * The RESTful API equivalent for [DbTaskTemplate].
@@ -16,6 +17,7 @@ import io.javalin.openapi.OpenApiIgnore
  * @author Luca Rossetto & Ralph Gasser
  * @version 2.0.0
  */
+@Serializable
 data class ApiTaskTemplate(
     val id: TaskTemplateId? = null,
     val name: String,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskType.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskType.kt
index f7f11f417..b0e075a73 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskType.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/tasks/ApiTaskType.kt
@@ -7,6 +7,7 @@ import com.fasterxml.jackson.databind.ObjectMapper
 import dev.dres.api.rest.types.template.tasks.options.*
 import dev.dres.data.model.template.task.DbTaskType
 import io.javalin.openapi.OpenApiIgnore
+import kotlinx.serialization.Serializable
 import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.StandardOpenOption
@@ -18,6 +19,7 @@ import java.nio.file.StandardOpenOption
  * @author Ralph Gasser & Loris Sauter
  * @version 1.1.0
  */
+@Serializable
 data class ApiTaskType(
     val name: String,
     val duration: Long,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeam.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeam.kt
index e4090fd52..0a0a0d082 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeam.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeam.kt
@@ -6,6 +6,7 @@ import dev.dres.api.rest.types.users.ApiUser
 import dev.dres.data.model.template.team.DbTeam
 import dev.dres.data.model.template.team.Team
 import dev.dres.data.model.template.team.TeamId
+import kotlinx.serialization.Serializable
 import java.awt.Image
 import java.awt.image.BufferedImage
 import java.io.ByteArrayInputStream
@@ -18,6 +19,7 @@ import javax.imageio.ImageIO
  * @author Loris Sauter
  * @version 1.0.0
  */
+@Serializable
 data class ApiTeam(
     val id: TeamId? = null,
     val name: String? = null,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeamGroup.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeamGroup.kt
index b538d4e6d..526e05232 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeamGroup.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/template/team/ApiTeamGroup.kt
@@ -3,6 +3,7 @@ package dev.dres.api.rest.types.template.team
 import dev.dres.data.model.template.team.DbTeamGroup
 import dev.dres.data.model.template.team.TeamAggregatorImpl
 import dev.dres.data.model.template.team.TeamGroupId
+import kotlinx.serialization.Serializable
 
 /**
  * A RESTful API representation of a [DbTeamGroup]
@@ -10,6 +11,7 @@ import dev.dres.data.model.template.team.TeamGroupId
  * @author Loris Sauter
  * @version 1.0.0
  */
+@Serializable
 data class ApiTeamGroup(
     val id: TeamGroupId? = null,
     val name: String? = null,
diff --git a/backend/src/main/kotlin/dev/dres/api/rest/types/users/ApiUser.kt b/backend/src/main/kotlin/dev/dres/api/rest/types/users/ApiUser.kt
index b91e7545d..09432170f 100644
--- a/backend/src/main/kotlin/dev/dres/api/rest/types/users/ApiUser.kt
+++ b/backend/src/main/kotlin/dev/dres/api/rest/types/users/ApiUser.kt
@@ -2,6 +2,7 @@ package dev.dres.api.rest.types.users
 
 import dev.dres.data.model.admin.DbUser
 import dev.dres.data.model.admin.UserId
+import kotlinx.serialization.Serializable
 
 /**
  * A RESTful API representation of a [DbUser]
@@ -9,4 +10,5 @@ import dev.dres.data.model.admin.UserId
  * @author Loris Sauter
  * @version 1.0.0
  */
+@Serializable
 data class ApiUser(val id: UserId? = null, val username: String? = null, val role: ApiRole? = null, var sessionId: String? = null)
\ No newline at end of file
diff --git a/backend/src/main/kotlin/dev/dres/data/model/run/ApiRunProperties.kt b/backend/src/main/kotlin/dev/dres/data/model/run/ApiRunProperties.kt
index 7d0e93ae0..f5ef49c66 100644
--- a/backend/src/main/kotlin/dev/dres/data/model/run/ApiRunProperties.kt
+++ b/backend/src/main/kotlin/dev/dres/data/model/run/ApiRunProperties.kt
@@ -1,8 +1,11 @@
 package dev.dres.data.model.run
 
+import kotlinx.serialization.Serializable
+
 /**
  *
  */
+@Serializable
 data class ApiRunProperties (
     val participantCanView: Boolean = true,
     val shuffleTasks: Boolean = false, //is only used for asynchronous runs
diff --git a/backend/src/main/kotlin/dev/dres/run/score/scoreboard/MaxNormalizingScoreBoard.kt b/backend/src/main/kotlin/dev/dres/run/score/scoreboard/MaxNormalizingScoreBoard.kt
index 626e45cf1..4357150ed 100644
--- a/backend/src/main/kotlin/dev/dres/run/score/scoreboard/MaxNormalizingScoreBoard.kt
+++ b/backend/src/main/kotlin/dev/dres/run/score/scoreboard/MaxNormalizingScoreBoard.kt
@@ -7,10 +7,7 @@ import dev.dres.data.model.run.interfaces.EvaluationRun
 import dev.dres.data.model.template.TemplateId
 import dev.dres.run.eventstream.EventStreamProcessor
 import dev.dres.run.eventstream.ScoreUpdateEvent
-import dev.dres.utilities.extensions.convertWriteLock
-import dev.dres.utilities.extensions.write
 import java.util.concurrent.locks.ReentrantReadWriteLock
-import java.util.concurrent.locks.StampedLock
 import kotlin.concurrent.read
 import kotlin.concurrent.write
 import kotlin.math.max
@@ -24,7 +21,7 @@ import kotlin.math.max
  */
 class MaxNormalizingScoreBoard(override val name: String, override val run: EvaluationRun, private val teamIds: List<TeamId>, private val taskFilter: (ApiTaskTemplate) -> Boolean, private val taskGroupName: String? = null, private val maxScoreNormalized: Double = 1000.0) : Scoreboard {
 
-    /** A [StampedLock] to synchronise access to this [MaxNormalizingScoreBoard]. */
+    /** A [ReentrantReadWriteLock] to synchronise access to this [MaxNormalizingScoreBoard]. */
     private val lock = ReentrantReadWriteLock()
 
     /** Tracks the score per [TeamId]. */
diff --git a/gradle.properties b/gradle.properties
index 92c5c1829..86cd46824 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -12,10 +12,10 @@ version_clikt=4.1.0
 version_fastutil=8.5.12
 version_fuel=2.3.1
 version_jaffree=2022.06.03
-version_javalin=5.6.1
+version_javalin=5.6.3
 version_jline3=3.22.0
 version_junit=5.9.1
-version_kotlin=1.8.10
+version_kotlin=1.8.22
 version_kotlin_csv=1.9.1
 version_log4j=2.20.0
 version_picnic=0.6.0