diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index af1e89a18..681726cd6 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -11,6 +11,7 @@ plugins {
     id("com.google.android.gms.oss-licenses-plugin")
     id("kotlin-parcelize")
     id("com.google.devtools.ksp")
+    kotlin("plugin.serialization") version "1.9.10"
 }
 
 repositories {
@@ -215,6 +216,7 @@ dependencies {
 
     implementation(libs.kotlin.jdk8)
     implementation(libs.kotlin.immutable)
+    implementation(libs.kotlinx.serialization)
     implementation(libs.okhttp)
     implementation(libs.persistent.cookiejar)
     implementation(libs.gson)
diff --git a/app/src/main/java/org/tasks/backup/BackupContainer.kt b/app/src/main/java/org/tasks/backup/BackupContainer.kt
index 8f1e5bb5a..5e7568b01 100644
--- a/app/src/main/java/org/tasks/backup/BackupContainer.kt
+++ b/app/src/main/java/org/tasks/backup/BackupContainer.kt
@@ -1,8 +1,10 @@
 package org.tasks.backup
 
-import org.tasks.data.entity.Task
+import kotlinx.serialization.Serializable
 import org.tasks.backup.TasksJsonImporter.LegacyLocation
-import org.tasks.data.*
+import org.tasks.data.GoogleTask
+import org.tasks.data.GoogleTaskAccount
+import org.tasks.data.GoogleTaskList
 import org.tasks.data.entity.Alarm
 import org.tasks.data.entity.Attachment
 import org.tasks.data.entity.CaldavAccount
@@ -13,10 +15,13 @@ import org.tasks.data.entity.Geofence
 import org.tasks.data.entity.Place
 import org.tasks.data.entity.Tag
 import org.tasks.data.entity.TagData
+import org.tasks.data.entity.Task
 import org.tasks.data.entity.TaskAttachment
 import org.tasks.data.entity.TaskListMetadata
 import org.tasks.data.entity.UserActivity
 
+@Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
+@Serializable
 class BackupContainer(
     val tasks: List<TaskBackup>?,
     val places: List<Place>?,
@@ -30,10 +35,11 @@ class BackupContainer(
     val longPrefs: Map<String, java.lang.Long>?,
     val stringPrefs: Map<String, String>?,
     val boolPrefs: Map<String, java.lang.Boolean>?,
-    val setPrefs: Map<String, java.util.Set<*>>?,
+    val setPrefs: Map<String, java.util.Set<String>>?,
     val googleTaskAccounts: List<GoogleTaskAccount>? = emptyList(),
     val googleTaskLists: List<GoogleTaskList>? = emptyList(),
 ) {
+    @Serializable
     class TaskBackup(
         val task: Task,
         val alarms: List<Alarm>,
diff --git a/app/src/main/java/org/tasks/backup/TasksJsonExporter.kt b/app/src/main/java/org/tasks/backup/TasksJsonExporter.kt
index 2b6e4711c..0ba41c4ba 100755
--- a/app/src/main/java/org/tasks/backup/TasksJsonExporter.kt
+++ b/app/src/main/java/org/tasks/backup/TasksJsonExporter.kt
@@ -7,10 +7,12 @@ import android.content.Context
 import android.net.Uri
 import android.os.Handler
 import com.google.common.io.Files
-import com.google.gson.Gson
-import com.google.gson.GsonBuilder
 import com.todoroo.andlib.utility.DialogUtilities
-import org.tasks.data.entity.Task
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.encodeToJsonElement
 import org.tasks.BuildConfig
 import org.tasks.R
 import org.tasks.backup.BackupContainer.TaskBackup
@@ -26,6 +28,7 @@ import org.tasks.data.dao.TaskAttachmentDao
 import org.tasks.data.dao.TaskDao
 import org.tasks.data.dao.TaskListMetadataDao
 import org.tasks.data.dao.UserActivityDao
+import org.tasks.data.entity.Task
 import org.tasks.date.DateTimeUtils.newDateTime
 import org.tasks.extensions.Context.toast
 import org.tasks.files.FileHelper
@@ -132,27 +135,32 @@ class TasksJsonExporter @Inject constructor(
                         vtodoCache.getVtodo( caldavTasks.firstOrNull { !it.isDeleted() })
                     ))
         }
-        val data: MutableMap<String, Any> = HashMap()
-        data["version"] = BuildConfig.VERSION_CODE
-        data["timestamp"] = currentTimeMillis()
-        data["data"] = BackupContainer(
-                taskBackups,
-                locationDao.getPlaces(),
-                tagDataDao.getAll(),
-                filterDao.getFilters(),
-                caldavDao.getAccounts(),
-                caldavDao.getCalendars(),
-                taskListMetadataDao.getAll(),
-                taskAttachmentDao.getAttachments(),
-                preferences.getPrefs(Integer::class.java),
-                preferences.getPrefs(java.lang.Long::class.java),
-                preferences.getPrefs(String::class.java),
-                preferences.getPrefs(java.lang.Boolean::class.java),
-                preferences.getPrefs(java.util.Set::class.java),
+        val data = JsonObject(
+            mapOf(
+                "version" to JsonPrimitive(BuildConfig.VERSION_CODE),
+                "timestamp" to JsonPrimitive(currentTimeMillis()),
+                "data" to Json.encodeToJsonElement(
+                    BackupContainer(
+                        taskBackups,
+                        locationDao.getPlaces(),
+                        tagDataDao.getAll(),
+                        filterDao.getFilters(),
+                        caldavDao.getAccounts(),
+                        caldavDao.getCalendars(),
+                        taskListMetadataDao.getAll(),
+                        taskAttachmentDao.getAttachments(),
+                        preferences.getPrefs(Integer::class.java),
+                        preferences.getPrefs(java.lang.Long::class.java),
+                        preferences.getPrefs(String::class.java),
+                        preferences.getPrefs(java.lang.Boolean::class.java),
+                        preferences.getPrefs(java.util.Set::class.java) as Map<String, java.util.Set<String>>,
+                    )
+                )
+            )
         )
         val out = OutputStreamWriter(os, UTF_8)
-        val gson = if (BuildConfig.DEBUG) GsonBuilder().setPrettyPrinting().create() else Gson()
-        out.write(gson.toJson(data))
+        val json = if (BuildConfig.DEBUG) Json { prettyPrint = true } else Json
+        out.write(json.encodeToString(data))
         out.close()
         exportCount = taskBackups.size
     }
diff --git a/app/src/main/java/org/tasks/backup/TasksJsonImporter.kt b/app/src/main/java/org/tasks/backup/TasksJsonImporter.kt
index 48d6873ee..fb2375b33 100644
--- a/app/src/main/java/org/tasks/backup/TasksJsonImporter.kt
+++ b/app/src/main/java/org/tasks/backup/TasksJsonImporter.kt
@@ -4,10 +4,7 @@ import android.app.ProgressDialog
 import android.content.Context
 import android.net.Uri
 import android.os.Handler
-import com.google.gson.Gson
-import com.google.gson.JsonObject
 import com.todoroo.astrid.dao.TaskDao
-import org.tasks.data.entity.Task
 import com.todoroo.astrid.service.TaskCreator.Companion.getDefaultAlarms
 import com.todoroo.astrid.service.TaskMover
 import com.todoroo.astrid.service.Upgrade_13_2
@@ -16,27 +13,34 @@ import com.todoroo.astrid.service.Upgrader.Companion.V12_4
 import com.todoroo.astrid.service.Upgrader.Companion.V12_8
 import com.todoroo.astrid.service.Upgrader.Companion.V6_4
 import com.todoroo.astrid.service.Upgrader.Companion.getAndroidColor
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.decodeFromJsonElement
+import kotlinx.serialization.json.int
+import kotlinx.serialization.json.jsonObject
+import kotlinx.serialization.json.jsonPrimitive
 import org.tasks.LocalBroadcastManager
 import org.tasks.R
 import org.tasks.caldav.VtodoCache
 import org.tasks.data.dao.AlarmDao
+import org.tasks.data.dao.CaldavDao
+import org.tasks.data.dao.FilterDao
+import org.tasks.data.dao.LocationDao
+import org.tasks.data.dao.TagDao
+import org.tasks.data.dao.TagDataDao
+import org.tasks.data.dao.TaskAttachmentDao
+import org.tasks.data.dao.TaskListMetadataDao
+import org.tasks.data.dao.UserActivityDao
 import org.tasks.data.entity.Attachment
 import org.tasks.data.entity.CaldavAccount
 import org.tasks.data.entity.CaldavAccount.Companion.TYPE_GOOGLE_TASKS
 import org.tasks.data.entity.CaldavCalendar
-import org.tasks.data.dao.CaldavDao
 import org.tasks.data.entity.CaldavTask
-import org.tasks.data.dao.FilterDao
 import org.tasks.data.entity.Geofence
-import org.tasks.data.dao.LocationDao
 import org.tasks.data.entity.Place
 import org.tasks.data.entity.Tag
-import org.tasks.data.dao.TagDao
 import org.tasks.data.entity.TagData
-import org.tasks.data.dao.TagDataDao
-import org.tasks.data.dao.TaskAttachmentDao
-import org.tasks.data.dao.TaskListMetadataDao
-import org.tasks.data.dao.UserActivityDao
+import org.tasks.data.entity.Task
 import org.tasks.db.Migrations.repeatFrom
 import org.tasks.db.Migrations.withoutFrom
 import org.tasks.filters.FilterCriteriaProvider
@@ -78,18 +82,17 @@ class TasksJsonImporter @Inject constructor(
 
     suspend fun importTasks(context: Context, backupFile: Uri?, progressDialog: ProgressDialog?): ImportResult {
         val handler = Handler(context.mainLooper)
-        val gson = Gson()
         val `is`: InputStream? = try {
             context.contentResolver.openInputStream(backupFile!!)
         } catch (e: FileNotFoundException) {
             throw IllegalStateException(e)
         }
         val reader = InputStreamReader(`is`, TasksJsonExporter.UTF_8)
-        val input = gson.fromJson(reader, JsonObject::class.java)
+        val input = Json.parseToJsonElement(reader.readText())
         try {
-            val data = input["data"]
-            val version = input["version"].asInt
-            val backupContainer = gson.fromJson(data, BackupContainer::class.java)
+            val data = input.jsonObject["data"]!!
+            val version = input.jsonObject["version"]!!.jsonPrimitive.int
+            val backupContainer = Json.decodeFromJsonElement<BackupContainer>(data)
             backupContainer.tags?.forEach { tagData ->
                 findTagData(tagData)?.let {
                     return@forEach
@@ -345,6 +348,7 @@ class TasksJsonImporter @Inject constructor(
         var skipCount = 0
     }
 
+    @Serializable
     class LegacyLocation {
         var name: String? = null
         var address: String? = null
diff --git a/data/build.gradle.kts b/data/build.gradle.kts
index 33e7e44b3..46e48ee8c 100644
--- a/data/build.gradle.kts
+++ b/data/build.gradle.kts
@@ -3,6 +3,7 @@ plugins {
     kotlin("android")
     id("com.google.devtools.ksp")
     id("kotlin-parcelize")
+    kotlin("plugin.serialization") version "1.9.10"
 }
 
 repositories {
@@ -51,7 +52,7 @@ android {
 dependencies {
     implementation(libs.androidx.lifecycle.livedata)
     implementation(libs.androidx.room)
-    implementation(libs.gson)
+    implementation(libs.kotlinx.serialization)
     implementation(libs.timber)
     ksp(libs.androidx.room.compiler)
 }
\ No newline at end of file
diff --git a/data/src/main/kotlin/org/tasks/data/GoogleTask.kt b/data/src/main/kotlin/org/tasks/data/GoogleTask.kt
index 60a0b68da..2ac53cde4 100644
--- a/data/src/main/kotlin/org/tasks/data/GoogleTask.kt
+++ b/data/src/main/kotlin/org/tasks/data/GoogleTask.kt
@@ -1,6 +1,9 @@
 package org.tasks.data
 
+import kotlinx.serialization.Serializable
+
 @Deprecated("For backup use only")
+@Serializable
 data class GoogleTask(
     var remoteId: String? = "",
     var listId: String? = "",
diff --git a/data/src/main/kotlin/org/tasks/data/GoogleTaskAccount.kt b/data/src/main/kotlin/org/tasks/data/GoogleTaskAccount.kt
index 1946961a9..1ecd79dfe 100644
--- a/data/src/main/kotlin/org/tasks/data/GoogleTaskAccount.kt
+++ b/data/src/main/kotlin/org/tasks/data/GoogleTaskAccount.kt
@@ -1,6 +1,9 @@
 package org.tasks.data
 
+import kotlinx.serialization.Serializable
+
 @Deprecated("Only used for backup migration")
+@Serializable
 data class GoogleTaskAccount(
     var account: String? = null,
     var etag: String? = null,
diff --git a/data/src/main/kotlin/org/tasks/data/GoogleTaskList.kt b/data/src/main/kotlin/org/tasks/data/GoogleTaskList.kt
index 10c9c70e5..5cb88bdbc 100644
--- a/data/src/main/kotlin/org/tasks/data/GoogleTaskList.kt
+++ b/data/src/main/kotlin/org/tasks/data/GoogleTaskList.kt
@@ -1,6 +1,9 @@
 package org.tasks.data
 
+import kotlinx.serialization.Serializable
+
 @Deprecated("Only used for backup migration")
+@Serializable
 data class GoogleTaskList(
     var account: String? = null,
     var remoteId: String? = null,
diff --git a/data/src/main/kotlin/org/tasks/data/entity/Alarm.kt b/data/src/main/kotlin/org/tasks/data/entity/Alarm.kt
index 0a772a1b6..003e6a869 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/Alarm.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/Alarm.kt
@@ -7,10 +7,13 @@ import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Ignore
 import androidx.room.PrimaryKey
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.tasks.data.db.Table
 import org.tasks.time.printTimestamp
 import java.util.concurrent.TimeUnit
 
+@Serializable
 @Entity(
     tableName = Alarm.TABLE_NAME,
     foreignKeys = [
diff --git a/data/src/main/kotlin/org/tasks/data/entity/Attachment.kt b/data/src/main/kotlin/org/tasks/data/entity/Attachment.kt
index 0c7bfe568..5a6418a9d 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/Attachment.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/Attachment.kt
@@ -5,7 +5,11 @@ import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Index
 import androidx.room.PrimaryKey
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
+import org.tasks.data.entity.Task.Companion.NO_ID
 
+@Serializable
 @Entity(
     tableName = "attachment",
     foreignKeys = [
@@ -31,10 +35,10 @@ data class Attachment(
     val id: Long? = null,
     @ColumnInfo(name = "task", index = true)
     @Transient
-    val task: Long,
+    val task: Long = NO_ID,
     @ColumnInfo(name = "file", index = true)
     @Transient
-    val fileId: Long,
+    val fileId: Long = NO_ID,
     @ColumnInfo(name = "file_uuid")
     val attachmentUid: String,
 )
\ No newline at end of file
diff --git a/data/src/main/kotlin/org/tasks/data/entity/CaldavAccount.kt b/data/src/main/kotlin/org/tasks/data/entity/CaldavAccount.kt
index 2262b1d2c..374780768 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/CaldavAccount.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/CaldavAccount.kt
@@ -4,10 +4,13 @@ import android.os.Parcelable
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.PrimaryKey
-import org.tasks.data.db.Table
 import kotlinx.parcelize.Parcelize
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
+import org.tasks.data.db.Table
 import java.net.HttpURLConnection
 
+@Serializable
 @Parcelize
 @Entity(tableName = "caldav_accounts")
 data class CaldavAccount(
diff --git a/data/src/main/kotlin/org/tasks/data/entity/CaldavCalendar.kt b/data/src/main/kotlin/org/tasks/data/entity/CaldavCalendar.kt
index 1bb3f68f3..f189ddfe1 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/CaldavCalendar.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/CaldavCalendar.kt
@@ -4,11 +4,14 @@ import android.os.Parcelable
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.PrimaryKey
-import org.tasks.data.db.Table
 import kotlinx.parcelize.Parcelize
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.tasks.data.LIST
 import org.tasks.data.NO_ORDER
+import org.tasks.data.db.Table
 
+@Serializable
 @Parcelize
 @Entity(tableName = "caldav_lists")
 data class CaldavCalendar(
diff --git a/data/src/main/kotlin/org/tasks/data/entity/CaldavTask.kt b/data/src/main/kotlin/org/tasks/data/entity/CaldavTask.kt
index 0a31b744c..dcb8965be 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/CaldavTask.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/CaldavTask.kt
@@ -4,9 +4,13 @@ import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.PrimaryKey
-import org.tasks.data.db.Table
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.tasks.data.UUIDHelper
+import org.tasks.data.db.Table
+import org.tasks.data.entity.Task.Companion.NO_ID
 
+@Serializable
 @Entity(
     tableName = "caldav_tasks",
     foreignKeys = [
@@ -25,7 +29,7 @@ data class CaldavTask(
     val id: Long = 0,
     @ColumnInfo(name = "cd_task", index = true)
     @Transient
-    val task: Long,
+    val task: Long = NO_ID,
     @ColumnInfo(name = "cd_calendar")
     var calendar: String?,
     @ColumnInfo(name = "cd_remote_id")
diff --git a/data/src/main/kotlin/org/tasks/data/entity/Filter.kt b/data/src/main/kotlin/org/tasks/data/entity/Filter.kt
index 1c8a1b1a5..b342a8638 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/Filter.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/Filter.kt
@@ -5,8 +5,11 @@ import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.PrimaryKey
 import kotlinx.parcelize.Parcelize
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.tasks.data.NO_ORDER
 
+@Serializable
 @Parcelize
 @Entity(tableName = "filters")
 data class Filter(
diff --git a/data/src/main/kotlin/org/tasks/data/entity/Geofence.kt b/data/src/main/kotlin/org/tasks/data/entity/Geofence.kt
index 668db75f3..c9be5cc95 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/Geofence.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/Geofence.kt
@@ -6,10 +6,11 @@ import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Ignore
 import androidx.room.PrimaryKey
-import org.tasks.data.db.Table
 import kotlinx.parcelize.Parcelize
-import java.io.Serializable
+import kotlinx.serialization.Serializable
+import org.tasks.data.db.Table
 
+@Serializable
 @Parcelize
 @Entity(
     tableName = Geofence.TABLE_NAME,
@@ -36,7 +37,7 @@ data class Geofence(
     val isArrival: Boolean = false,
     @ColumnInfo(name = "departure")
     var isDeparture: Boolean = false,
-) : Serializable, Parcelable {
+) : java.io.Serializable, Parcelable {
     @Ignore
     constructor(
         task: Long,
diff --git a/data/src/main/kotlin/org/tasks/data/entity/Place.kt b/data/src/main/kotlin/org/tasks/data/entity/Place.kt
index 3899653cc..50d84af55 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/Place.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/Place.kt
@@ -6,14 +6,16 @@ import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.Index
 import androidx.room.PrimaryKey
-import org.tasks.data.db.Table
-import org.tasks.data.UUIDHelper
 import kotlinx.parcelize.Parcelize
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.tasks.data.NO_ORDER
-import java.io.Serializable
+import org.tasks.data.UUIDHelper
+import org.tasks.data.db.Table
 import java.util.regex.Pattern
 import kotlin.math.abs
 
+@Serializable
 @Parcelize
 @Entity(
     tableName = Place.TABLE_NAME,
@@ -48,7 +50,7 @@ data class Place(
     val order: Int = NO_ORDER,
     @ColumnInfo(name = "radius", defaultValue = "250")
     val radius: Int = 250,
-) : Serializable, Parcelable {
+) : java.io.Serializable, Parcelable {
     val displayName: String
         get() {
             if (!name.isNullOrEmpty() && !COORDS.matcher(name!!).matches()) {
diff --git a/data/src/main/kotlin/org/tasks/data/entity/Tag.kt b/data/src/main/kotlin/org/tasks/data/entity/Tag.kt
index 7d6b95715..6a111698d 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/Tag.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/Tag.kt
@@ -5,8 +5,11 @@ import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Ignore
 import androidx.room.PrimaryKey
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.tasks.data.db.Table
 
+@Serializable
 @Entity(
     tableName = "tags",
     foreignKeys = [
diff --git a/data/src/main/kotlin/org/tasks/data/entity/TagData.kt b/data/src/main/kotlin/org/tasks/data/entity/TagData.kt
index c98ae7175..d6c2c993d 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/TagData.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/TagData.kt
@@ -7,9 +7,12 @@ import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.Ignore
 import androidx.room.PrimaryKey
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.tasks.data.LABEL
 import org.tasks.data.NO_ORDER
 
+@Serializable
 @Entity(tableName = "tagdata")
 class TagData : Parcelable {
     @PrimaryKey(autoGenerate = true)
diff --git a/data/src/main/kotlin/org/tasks/data/entity/Task.kt b/data/src/main/kotlin/org/tasks/data/entity/Task.kt
index 3f7f0a26c..56bb3d30c 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/Task.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/Task.kt
@@ -7,23 +7,28 @@ import androidx.room.Entity
 import androidx.room.Ignore
 import androidx.room.Index
 import androidx.room.PrimaryKey
-import com.google.gson.annotations.SerializedName
-import org.tasks.data.db.Table
-import org.tasks.data.sql.Field
 import kotlinx.parcelize.Parcelize
 import kotlinx.parcelize.RawValue
+import kotlinx.serialization.ExperimentalSerializationApi
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
+import kotlinx.serialization.json.JsonNames
+import org.tasks.data.db.Table
+import org.tasks.data.sql.Field
 import timber.log.Timber
 
 const val SUPPRESS_SYNC = "suppress_sync"
 const val FORCE_CALDAV_SYNC = "force_caldav_sync"
 
+@Serializable
 @Parcelize
 @Entity(
         tableName = Task.TABLE_NAME,
         indices = [
             Index(name = "t_rid", value = ["remoteId"], unique = true),
             Index(name = "active_and_visible", value = ["completed", "deleted", "hideUntil"])])
-data class Task(
+data class Task @OptIn(ExperimentalSerializationApi::class) constructor(
     @PrimaryKey(autoGenerate = true)
     @ColumnInfo(name = "_id")
     @Transient
@@ -53,7 +58,8 @@ data class Task(
     @ColumnInfo(name = "timerStart")
     var timerStart: Long = 0L,
     @ColumnInfo(name = "notificationFlags")
-    @SerializedName("ringFlags", alternate = ["reminderFlags"])
+    @SerialName("ringFlags")
+    @JsonNames("reminderFlags")
     var ringFlags: Int = 0,
     @ColumnInfo(name = "lastNotified")
     var reminderLast: Long = 0L,
diff --git a/data/src/main/kotlin/org/tasks/data/entity/TaskAttachment.kt b/data/src/main/kotlin/org/tasks/data/entity/TaskAttachment.kt
index 59f56e144..27f170ba1 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/TaskAttachment.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/TaskAttachment.kt
@@ -4,9 +4,12 @@ import android.os.Parcelable
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.PrimaryKey
-import org.tasks.data.UUIDHelper
 import kotlinx.parcelize.Parcelize
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
+import org.tasks.data.UUIDHelper
 
+@Serializable
 @Parcelize
 @Entity(tableName = "attachment_file")
 data class TaskAttachment(
diff --git a/data/src/main/kotlin/org/tasks/data/entity/TaskListMetadata.kt b/data/src/main/kotlin/org/tasks/data/entity/TaskListMetadata.kt
index c7f454613..edd698e2b 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/TaskListMetadata.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/TaskListMetadata.kt
@@ -3,13 +3,10 @@ package org.tasks.data.entity
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.PrimaryKey
-import org.tasks.data.entity.Task
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 
-/**
- * Data Model which represents a user.
- *
- * @author Tim Su <tim></tim>@todoroo.com>
- */
+@Serializable
 @Entity(tableName = "task_list_metadata")
 class TaskListMetadata {
     @PrimaryKey(autoGenerate = true)
diff --git a/data/src/main/kotlin/org/tasks/data/entity/UserActivity.kt b/data/src/main/kotlin/org/tasks/data/entity/UserActivity.kt
index f21ff4924..3c6388f03 100644
--- a/data/src/main/kotlin/org/tasks/data/entity/UserActivity.kt
+++ b/data/src/main/kotlin/org/tasks/data/entity/UserActivity.kt
@@ -7,12 +7,15 @@ import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.Ignore
 import androidx.room.PrimaryKey
-import org.tasks.data.db.Table
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.json.JSONException
 import org.json.JSONObject
+import org.tasks.data.db.Table
 import timber.log.Timber
 import java.io.File
 
+@Serializable
 @Entity(tableName = "userActivity")
 class UserActivity : Parcelable {
     @PrimaryKey(autoGenerate = true)
diff --git a/deps_fdroid.txt b/deps_fdroid.txt
index 578e5072f..877ae25ef 100644
--- a/deps_fdroid.txt
+++ b/deps_fdroid.txt
@@ -240,7 +240,20 @@
 +|    |    +--- org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.1 -> 1.7.3 (*)
 +|    |    +--- androidx.room:room-common:2.6.1 (c)
 +|    |    \--- androidx.room:room-runtime:2.6.1 (c)
-+|    +--- com.google.code.gson:gson:2.10.1
++|    +--- org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.2
++|    |    \--- org.jetbrains.kotlinx:kotlinx-serialization-json-jvm:1.6.2
++|    |         +--- org.jetbrains.kotlin:kotlin-stdlib:1.9.21 -> 1.9.23 (*)
++|    |         +--- org.jetbrains.kotlinx:kotlinx-serialization-bom:1.6.2
++|    |         |    +--- org.jetbrains.kotlinx:kotlinx-serialization-core:1.6.2 (c)
++|    |         |    +--- org.jetbrains.kotlinx:kotlinx-serialization-json-jvm:1.6.2 (c)
++|    |         |    +--- org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.2 (c)
++|    |         |    \--- org.jetbrains.kotlinx:kotlinx-serialization-core-jvm:1.6.2 (c)
++|    |         +--- org.jetbrains.kotlin:kotlin-stdlib-common:1.9.21 -> 1.9.23 (*)
++|    |         \--- org.jetbrains.kotlinx:kotlinx-serialization-core:1.6.2
++|    |              \--- org.jetbrains.kotlinx:kotlinx-serialization-core-jvm:1.6.2
++|    |                   +--- org.jetbrains.kotlin:kotlin-stdlib:1.9.21 -> 1.9.23 (*)
++|    |                   +--- org.jetbrains.kotlinx:kotlinx-serialization-bom:1.6.2 (*)
++|    |                   \--- org.jetbrains.kotlin:kotlin-stdlib-common:1.9.21 -> 1.9.23 (*)
 +|    +--- com.jakewharton.timber:timber:5.0.1
 +|    |    +--- org.jetbrains.kotlin:kotlin-stdlib:1.5.21 -> 1.9.23 (*)
 +|    |    \--- org.jetbrains:annotations:20.1.0 -> 23.0.0
@@ -602,6 +615,7 @@
 ++--- org.jetbrains.kotlinx:kotlinx-collections-immutable:0.3.7
 +|    \--- org.jetbrains.kotlinx:kotlinx-collections-immutable-jvm:0.3.7
 +|         \--- org.jetbrains.kotlin:kotlin-stdlib:1.9.21 -> 1.9.23 (*)
+++--- org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.2 (*)
 ++--- com.squareup.okhttp3:okhttp:4.12.0 (*)
 ++--- com.github.franmontiel:PersistentCookieJar:1.0.1
 +|    \--- com.squareup.okhttp3:okhttp:3.1.2 -> 4.12.0 (*)
diff --git a/deps_googleplay.txt b/deps_googleplay.txt
index 85150aeb8..2618214a5 100644
--- a/deps_googleplay.txt
+++ b/deps_googleplay.txt
@@ -600,7 +600,20 @@
 +|    |    +--- org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.1 -> 1.7.3 (*)
 +|    |    +--- androidx.room:room-common:2.6.1 (c)
 +|    |    \--- androidx.room:room-runtime:2.6.1 (c)
-+|    +--- com.google.code.gson:gson:2.10.1
++|    +--- org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.2
++|    |    \--- org.jetbrains.kotlinx:kotlinx-serialization-json-jvm:1.6.2
++|    |         +--- org.jetbrains.kotlin:kotlin-stdlib:1.9.21 -> 1.9.23 (*)
++|    |         +--- org.jetbrains.kotlinx:kotlinx-serialization-bom:1.6.2
++|    |         |    +--- org.jetbrains.kotlinx:kotlinx-serialization-core:1.6.2 (c)
++|    |         |    +--- org.jetbrains.kotlinx:kotlinx-serialization-json-jvm:1.6.2 (c)
++|    |         |    +--- org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.2 (c)
++|    |         |    \--- org.jetbrains.kotlinx:kotlinx-serialization-core-jvm:1.6.2 (c)
++|    |         +--- org.jetbrains.kotlin:kotlin-stdlib-common:1.9.21 -> 1.9.23 (*)
++|    |         \--- org.jetbrains.kotlinx:kotlinx-serialization-core:1.6.2
++|    |              \--- org.jetbrains.kotlinx:kotlinx-serialization-core-jvm:1.6.2
++|    |                   +--- org.jetbrains.kotlin:kotlin-stdlib:1.9.21 -> 1.9.23 (*)
++|    |                   +--- org.jetbrains.kotlinx:kotlinx-serialization-bom:1.6.2 (*)
++|    |                   \--- org.jetbrains.kotlin:kotlin-stdlib-common:1.9.21 -> 1.9.23 (*)
 +|    +--- com.jakewharton.timber:timber:5.0.1
 +|    |    +--- org.jetbrains.kotlin:kotlin-stdlib:1.5.21 -> 1.9.23 (*)
 +|    |    \--- org.jetbrains:annotations:20.1.0 -> 23.0.0
@@ -831,6 +844,7 @@
 ++--- org.jetbrains.kotlinx:kotlinx-collections-immutable:0.3.7
 +|    \--- org.jetbrains.kotlinx:kotlinx-collections-immutable-jvm:0.3.7
 +|         \--- org.jetbrains.kotlin:kotlin-stdlib:1.9.21 -> 1.9.23 (*)
+++--- org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.2 (*)
 ++--- com.squareup.okhttp3:okhttp:4.12.0 (*)
 ++--- com.github.franmontiel:PersistentCookieJar:1.0.1
 +|    \--- com.squareup.okhttp3:okhttp:3.1.2 -> 4.12.0 (*)
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index fbc49cded..117f8f254 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -131,6 +131,7 @@ kotlin-immutable = { module = "org.jetbrains.kotlinx:kotlinx-collections-immutab
 kotlin-jdk8 = { module = "org.jetbrains.kotlin:kotlin-stdlib-jdk8", version.ref = "kotlin" }
 kotlin-reflect = { module = "org.jetbrains.kotlin:kotlin-reflect", version.ref = "kotlin" }
 kotlinx-coroutines-test = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-test", version.ref = "kotlinx-coroutines-test" }
+kotlinx-serialization = { module = "org.jetbrains.kotlinx:kotlinx-serialization-json", version = "1.6.2" }
 leakcanary = { module = "com.squareup.leakcanary:leakcanary-android", version.ref = "leakcanary" }
 locale = { module = "com.github.twofortyfouram:android-plugin-api-for-locale", version.ref = "locale" }
 make-it-easy = { module = "com.natpryce:make-it-easy", version.ref = "make-it-easy" }