diff --git a/app/build.gradle b/app/build.gradle
index daa6a7d41..9e40045c8 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -123,6 +123,7 @@ dependencies {
 	debugImplementation 'com.squareup.leakcanary:leakcanary-android:2.9.1'
 
 	testImplementation 'junit:junit:4.13.2'
+	testImplementation 'org.json:json:20220320'
 	testImplementation 'org.jetbrains.kotlinx:kotlinx-coroutines-test:1.6.4'
 
 	androidTestImplementation 'androidx.test:runner:1.4.0'
diff --git a/app/src/main/java/org/koitharu/kotatsu/bookmarks/data/BookmarkEntity.kt b/app/src/main/java/org/koitharu/kotatsu/bookmarks/data/BookmarkEntity.kt
index 1f348899b..f4bbba185 100644
--- a/app/src/main/java/org/koitharu/kotatsu/bookmarks/data/BookmarkEntity.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/bookmarks/data/BookmarkEntity.kt
@@ -17,7 +17,7 @@ import org.koitharu.kotatsu.core.db.entity.MangaEntity
 		),
 	]
 )
-class BookmarkEntity(
+data class BookmarkEntity(
 	@ColumnInfo(name = "manga_id", index = true) val mangaId: Long,
 	@ColumnInfo(name = "page_id", index = true) val pageId: Long,
 	@ColumnInfo(name = "chapter_id") val chapterId: Long,
diff --git a/app/src/main/java/org/koitharu/kotatsu/core/backup/BackupRepository.kt b/app/src/main/java/org/koitharu/kotatsu/core/backup/BackupRepository.kt
index 7212b8569..27dd10255 100644
--- a/app/src/main/java/org/koitharu/kotatsu/core/backup/BackupRepository.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/core/backup/BackupRepository.kt
@@ -1,14 +1,12 @@
 package org.koitharu.kotatsu.core.backup
 
+import androidx.room.withTransaction
 import org.json.JSONArray
 import org.json.JSONObject
 import org.koitharu.kotatsu.BuildConfig
 import org.koitharu.kotatsu.core.db.MangaDatabase
-import org.koitharu.kotatsu.core.db.entity.MangaEntity
-import org.koitharu.kotatsu.core.db.entity.TagEntity
-import org.koitharu.kotatsu.favourites.data.FavouriteCategoryEntity
-import org.koitharu.kotatsu.favourites.data.FavouriteEntity
-import org.koitharu.kotatsu.history.data.HistoryEntity
+import org.koitharu.kotatsu.parsers.util.json.JSONIterator
+import org.koitharu.kotatsu.parsers.util.json.mapJSON
 
 private const val PAGE_SIZE = 10
 
@@ -24,11 +22,11 @@ class BackupRepository(private val db: MangaDatabase) {
 			}
 			offset += history.size
 			for (item in history) {
-				val manga = item.manga.toJson()
+				val manga = JsonSerializer(item.manga).toJson()
 				val tags = JSONArray()
-				item.tags.forEach { tags.put(it.toJson()) }
+				item.tags.forEach { tags.put(JsonSerializer(it).toJson()) }
 				manga.put("tags", tags)
-				val json = item.history.toJson()
+				val json = JsonSerializer(item.history).toJson()
 				json.put("manga", manga)
 				entry.data.put(json)
 			}
@@ -40,7 +38,7 @@ class BackupRepository(private val db: MangaDatabase) {
 		val entry = BackupEntry(BackupEntry.CATEGORIES, JSONArray())
 		val categories = db.favouriteCategoriesDao.findAll()
 		for (item in categories) {
-			entry.data.put(item.toJson())
+			entry.data.put(JsonSerializer(item).toJson())
 		}
 		return entry
 	}
@@ -55,11 +53,11 @@ class BackupRepository(private val db: MangaDatabase) {
 			}
 			offset += favourites.size
 			for (item in favourites) {
-				val manga = item.manga.toJson()
+				val manga = JsonSerializer(item.manga).toJson()
 				val tags = JSONArray()
-				item.tags.forEach { tags.put(it.toJson()) }
+				item.tags.forEach { tags.put(JsonSerializer(it).toJson()) }
 				manga.put("tags", tags)
-				val json = item.favourite.toJson()
+				val json = JsonSerializer(item.favourite).toJson()
 				json.put("manga", manga)
 				entry.data.put(json)
 			}
@@ -77,60 +75,54 @@ class BackupRepository(private val db: MangaDatabase) {
 		return entry
 	}
 
-	private fun MangaEntity.toJson(): JSONObject {
-		val jo = JSONObject()
-		jo.put("id", id)
-		jo.put("title", title)
-		jo.put("alt_title", altTitle)
-		jo.put("url", url)
-		jo.put("public_url", publicUrl)
-		jo.put("rating", rating)
-		jo.put("nsfw", isNsfw)
-		jo.put("cover_url", coverUrl)
-		jo.put("large_cover_url", largeCoverUrl)
-		jo.put("state", state)
-		jo.put("author", author)
-		jo.put("source", source)
-		return jo
+	suspend fun restoreHistory(entry: BackupEntry): CompositeResult {
+		val result = CompositeResult()
+		for (item in entry.data.JSONIterator()) {
+			val mangaJson = item.getJSONObject("manga")
+			val manga = JsonDeserializer(mangaJson).toMangaEntity()
+			val tags = mangaJson.getJSONArray("tags").mapJSON {
+				JsonDeserializer(it).toTagEntity()
+			}
+			val history = JsonDeserializer(item).toHistoryEntity()
+			result += runCatching {
+				db.withTransaction {
+					db.tagsDao.upsert(tags)
+					db.mangaDao.upsert(manga, tags)
+					db.historyDao.upsert(history)
+				}
+			}
+		}
+		return result
 	}
 
-	private fun TagEntity.toJson(): JSONObject {
-		val jo = JSONObject()
-		jo.put("id", id)
-		jo.put("title", title)
-		jo.put("key", key)
-		jo.put("source", source)
-		return jo
+	suspend fun restoreCategories(entry: BackupEntry): CompositeResult {
+		val result = CompositeResult()
+		for (item in entry.data.JSONIterator()) {
+			val category = JsonDeserializer(item).toFavouriteCategoryEntity()
+			result += runCatching {
+				db.favouriteCategoriesDao.upsert(category)
+			}
+		}
+		return result
 	}
 
-	private fun HistoryEntity.toJson(): JSONObject {
-		val jo = JSONObject()
-		jo.put("manga_id", mangaId)
-		jo.put("created_at", createdAt)
-		jo.put("updated_at", updatedAt)
-		jo.put("chapter_id", chapterId)
-		jo.put("page", page)
-		jo.put("scroll", scroll)
-		jo.put("percent", percent)
-		return jo
-	}
-
-	private fun FavouriteCategoryEntity.toJson(): JSONObject {
-		val jo = JSONObject()
-		jo.put("category_id", categoryId)
-		jo.put("created_at", createdAt)
-		jo.put("sort_key", sortKey)
-		jo.put("title", title)
-		jo.put("order", order)
-		jo.put("track", track)
-		return jo
-	}
-
-	private fun FavouriteEntity.toJson(): JSONObject {
-		val jo = JSONObject()
-		jo.put("manga_id", mangaId)
-		jo.put("category_id", categoryId)
-		jo.put("created_at", createdAt)
-		return jo
+	suspend fun restoreFavourites(entry: BackupEntry): CompositeResult {
+		val result = CompositeResult()
+		for (item in entry.data.JSONIterator()) {
+			val mangaJson = item.getJSONObject("manga")
+			val manga = JsonDeserializer(mangaJson).toMangaEntity()
+			val tags = mangaJson.getJSONArray("tags").mapJSON {
+				JsonDeserializer(it).toTagEntity()
+			}
+			val favourite = JsonDeserializer(item).toFavouriteEntity()
+			result += runCatching {
+				db.withTransaction {
+					db.tagsDao.upsert(tags)
+					db.mangaDao.upsert(manga, tags)
+					db.favouritesDao.upsert(favourite)
+				}
+			}
+		}
+		return result
 	}
 }
\ No newline at end of file
diff --git a/app/src/main/java/org/koitharu/kotatsu/core/backup/JsonDeserializer.kt b/app/src/main/java/org/koitharu/kotatsu/core/backup/JsonDeserializer.kt
new file mode 100644
index 000000000..96463e4a5
--- /dev/null
+++ b/app/src/main/java/org/koitharu/kotatsu/core/backup/JsonDeserializer.kt
@@ -0,0 +1,62 @@
+package org.koitharu.kotatsu.core.backup
+
+import org.json.JSONObject
+import org.koitharu.kotatsu.core.db.entity.MangaEntity
+import org.koitharu.kotatsu.core.db.entity.TagEntity
+import org.koitharu.kotatsu.favourites.data.FavouriteCategoryEntity
+import org.koitharu.kotatsu.favourites.data.FavouriteEntity
+import org.koitharu.kotatsu.history.data.HistoryEntity
+import org.koitharu.kotatsu.parsers.model.SortOrder
+import org.koitharu.kotatsu.parsers.util.json.getBooleanOrDefault
+import org.koitharu.kotatsu.parsers.util.json.getFloatOrDefault
+import org.koitharu.kotatsu.parsers.util.json.getStringOrNull
+
+class JsonDeserializer(private val json: JSONObject) {
+
+	fun toFavouriteEntity() = FavouriteEntity(
+		mangaId = json.getLong("manga_id"),
+		categoryId = json.getLong("category_id"),
+		createdAt = json.getLong("created_at"),
+	)
+
+	fun toMangaEntity() = MangaEntity(
+		id = json.getLong("id"),
+		title = json.getString("title"),
+		altTitle = json.getStringOrNull("alt_title"),
+		url = json.getString("url"),
+		publicUrl = json.getStringOrNull("public_url").orEmpty(),
+		rating = json.getDouble("rating").toFloat(),
+		isNsfw = json.getBooleanOrDefault("nsfw", false),
+		coverUrl = json.getString("cover_url"),
+		largeCoverUrl = json.getStringOrNull("large_cover_url"),
+		state = json.getStringOrNull("state"),
+		author = json.getStringOrNull("author"),
+		source = json.getString("source")
+	)
+
+	fun toTagEntity() = TagEntity(
+		id = json.getLong("id"),
+		title = json.getString("title"),
+		key = json.getString("key"),
+		source = json.getString("source")
+	)
+
+	fun toHistoryEntity() = HistoryEntity(
+		mangaId = json.getLong("manga_id"),
+		createdAt = json.getLong("created_at"),
+		updatedAt = json.getLong("updated_at"),
+		chapterId = json.getLong("chapter_id"),
+		page = json.getInt("page"),
+		scroll = json.getDouble("scroll").toFloat(),
+		percent = json.getFloatOrDefault("percent", -1f),
+	)
+
+	fun toFavouriteCategoryEntity() = FavouriteCategoryEntity(
+		categoryId = json.getInt("category_id"),
+		createdAt = json.getLong("created_at"),
+		sortKey = json.getInt("sort_key"),
+		title = json.getString("title"),
+		order = json.getStringOrNull("order") ?: SortOrder.NEWEST.name,
+		track = json.getBooleanOrDefault("track", true),
+	)
+}
\ No newline at end of file
diff --git a/app/src/main/java/org/koitharu/kotatsu/core/backup/JsonSerializer.kt b/app/src/main/java/org/koitharu/kotatsu/core/backup/JsonSerializer.kt
new file mode 100644
index 000000000..b6a035e87
--- /dev/null
+++ b/app/src/main/java/org/koitharu/kotatsu/core/backup/JsonSerializer.kt
@@ -0,0 +1,70 @@
+package org.koitharu.kotatsu.core.backup
+
+import org.json.JSONObject
+import org.koitharu.kotatsu.core.db.entity.MangaEntity
+import org.koitharu.kotatsu.core.db.entity.TagEntity
+import org.koitharu.kotatsu.favourites.data.FavouriteCategoryEntity
+import org.koitharu.kotatsu.favourites.data.FavouriteEntity
+import org.koitharu.kotatsu.history.data.HistoryEntity
+
+class JsonSerializer private constructor(private val json: JSONObject) {
+
+	constructor(e: FavouriteEntity) : this(
+		JSONObject().apply {
+			put("manga_id", e.mangaId)
+			put("category_id", e.categoryId)
+			put("created_at", e.createdAt)
+		}
+	)
+
+	constructor(e: FavouriteCategoryEntity) : this(
+		JSONObject().apply {
+			put("category_id", e.categoryId)
+			put("created_at", e.createdAt)
+			put("sort_key", e.sortKey)
+			put("title", e.title)
+			put("order", e.order)
+			put("track", e.track)
+		}
+	)
+
+	constructor(e: HistoryEntity) : this(
+		JSONObject().apply {
+			put("manga_id", e.mangaId)
+			put("created_at", e.createdAt)
+			put("updated_at", e.updatedAt)
+			put("chapter_id", e.chapterId)
+			put("page", e.page)
+			put("scroll", e.scroll)
+			put("percent", e.percent)
+		}
+	)
+
+	constructor(e: TagEntity) : this(
+		JSONObject().apply {
+			put("id", e.id)
+			put("title", e.title)
+			put("key", e.key)
+			put("source", e.source)
+		}
+	)
+
+	constructor(e: MangaEntity) : this(
+		JSONObject().apply {
+			put("id", e.id)
+			put("title", e.title)
+			put("alt_title", e.altTitle)
+			put("url", e.url)
+			put("public_url", e.publicUrl)
+			put("rating", e.rating)
+			put("nsfw", e.isNsfw)
+			put("cover_url", e.coverUrl)
+			put("large_cover_url", e.largeCoverUrl)
+			put("state", e.state)
+			put("author", e.author)
+			put("source", e.source)
+		}
+	)
+
+	fun toJson(): JSONObject = json
+}
\ No newline at end of file
diff --git a/app/src/main/java/org/koitharu/kotatsu/core/backup/RestoreRepository.kt b/app/src/main/java/org/koitharu/kotatsu/core/backup/RestoreRepository.kt
deleted file mode 100644
index 4e20b955f..000000000
--- a/app/src/main/java/org/koitharu/kotatsu/core/backup/RestoreRepository.kt
+++ /dev/null
@@ -1,113 +0,0 @@
-package org.koitharu.kotatsu.core.backup
-
-import androidx.room.withTransaction
-import org.json.JSONObject
-import org.koitharu.kotatsu.core.db.MangaDatabase
-import org.koitharu.kotatsu.core.db.entity.MangaEntity
-import org.koitharu.kotatsu.core.db.entity.TagEntity
-import org.koitharu.kotatsu.favourites.data.FavouriteCategoryEntity
-import org.koitharu.kotatsu.favourites.data.FavouriteEntity
-import org.koitharu.kotatsu.history.data.HistoryEntity
-import org.koitharu.kotatsu.parsers.model.SortOrder
-import org.koitharu.kotatsu.parsers.util.json.*
-
-class RestoreRepository(private val db: MangaDatabase) {
-
-	suspend fun upsertHistory(entry: BackupEntry): CompositeResult {
-		val result = CompositeResult()
-		for (item in entry.data.JSONIterator()) {
-			val mangaJson = item.getJSONObject("manga")
-			val manga = parseManga(mangaJson)
-			val tags = mangaJson.getJSONArray("tags").mapJSON {
-				parseTag(it)
-			}
-			val history = parseHistory(item)
-			result += runCatching {
-				db.withTransaction {
-					db.tagsDao.upsert(tags)
-					db.mangaDao.upsert(manga, tags)
-					db.historyDao.upsert(history)
-				}
-			}
-		}
-		return result
-	}
-
-	suspend fun upsertCategories(entry: BackupEntry): CompositeResult {
-		val result = CompositeResult()
-		for (item in entry.data.JSONIterator()) {
-			val category = parseCategory(item)
-			result += runCatching {
-				db.favouriteCategoriesDao.upsert(category)
-			}
-		}
-		return result
-	}
-
-	suspend fun upsertFavourites(entry: BackupEntry): CompositeResult {
-		val result = CompositeResult()
-		for (item in entry.data.JSONIterator()) {
-			val mangaJson = item.getJSONObject("manga")
-			val manga = parseManga(mangaJson)
-			val tags = mangaJson.getJSONArray("tags").mapJSON {
-				parseTag(it)
-			}
-			val favourite = parseFavourite(item)
-			result += runCatching {
-				db.withTransaction {
-					db.tagsDao.upsert(tags)
-					db.mangaDao.upsert(manga, tags)
-					db.favouritesDao.upsert(favourite)
-				}
-			}
-		}
-		return result
-	}
-
-	private fun parseManga(json: JSONObject) = MangaEntity(
-		id = json.getLong("id"),
-		title = json.getString("title"),
-		altTitle = json.getStringOrNull("alt_title"),
-		url = json.getString("url"),
-		publicUrl = json.getStringOrNull("public_url").orEmpty(),
-		rating = json.getDouble("rating").toFloat(),
-		isNsfw = json.getBooleanOrDefault("nsfw", false),
-		coverUrl = json.getString("cover_url"),
-		largeCoverUrl = json.getStringOrNull("large_cover_url"),
-		state = json.getStringOrNull("state"),
-		author = json.getStringOrNull("author"),
-		source = json.getString("source")
-	)
-
-	private fun parseTag(json: JSONObject) = TagEntity(
-		id = json.getLong("id"),
-		title = json.getString("title"),
-		key = json.getString("key"),
-		source = json.getString("source")
-	)
-
-	private fun parseHistory(json: JSONObject) = HistoryEntity(
-		mangaId = json.getLong("manga_id"),
-		createdAt = json.getLong("created_at"),
-		updatedAt = json.getLong("updated_at"),
-		chapterId = json.getLong("chapter_id"),
-		page = json.getInt("page"),
-		scroll = json.getDouble("scroll").toFloat(),
-		percent = json.getFloatOrDefault("percent", -1f),
-	)
-
-	private fun parseCategory(json: JSONObject) = FavouriteCategoryEntity(
-		categoryId = json.getInt("category_id"),
-		createdAt = json.getLong("created_at"),
-		sortKey = json.getInt("sort_key"),
-		title = json.getString("title"),
-		order = json.getStringOrNull("order") ?: SortOrder.NEWEST.name,
-		track = json.getBooleanOrDefault("track", true),
-	)
-
-	private fun parseFavourite(json: JSONObject) = FavouriteEntity(
-		mangaId = json.getLong("manga_id"),
-		categoryId = json.getLong("category_id"),
-		createdAt = json.getLong("created_at")
-	)
-}
\ No newline at end of file
diff --git a/app/src/main/java/org/koitharu/kotatsu/core/db/entity/MangaEntity.kt b/app/src/main/java/org/koitharu/kotatsu/core/db/entity/MangaEntity.kt
index c425f0e68..bfe64375f 100644
--- a/app/src/main/java/org/koitharu/kotatsu/core/db/entity/MangaEntity.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/core/db/entity/MangaEntity.kt
@@ -5,7 +5,7 @@ import androidx.room.Entity
 import androidx.room.PrimaryKey
 
 @Entity(tableName = "manga")
-class MangaEntity(
+data class MangaEntity(
 	@PrimaryKey(autoGenerate = false)
 	@ColumnInfo(name = "manga_id") val id: Long,
 	@ColumnInfo(name = "title") val title: String,
diff --git a/app/src/main/java/org/koitharu/kotatsu/core/db/entity/TagEntity.kt b/app/src/main/java/org/koitharu/kotatsu/core/db/entity/TagEntity.kt
index fe813a02b..8c5e927c4 100644
--- a/app/src/main/java/org/koitharu/kotatsu/core/db/entity/TagEntity.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/core/db/entity/TagEntity.kt
@@ -5,7 +5,7 @@ import androidx.room.Entity
 import androidx.room.PrimaryKey
 
 @Entity(tableName = "tags")
-class TagEntity(
+data class TagEntity(
 	@PrimaryKey(autoGenerate = false)
 	@ColumnInfo(name = "tag_id") val id: Long,
 	@ColumnInfo(name = "title") val title: String,
diff --git a/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteCategoryEntity.kt b/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteCategoryEntity.kt
index 5fe02f019..5cc62dbae 100644
--- a/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteCategoryEntity.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteCategoryEntity.kt
@@ -5,7 +5,7 @@ import androidx.room.Entity
 import androidx.room.PrimaryKey
 
 @Entity(tableName = "favourite_categories")
-class FavouriteCategoryEntity(
+data class FavouriteCategoryEntity(
 	@PrimaryKey(autoGenerate = true)
 	@ColumnInfo(name = "category_id") val categoryId: Int,
 	@ColumnInfo(name = "created_at") val createdAt: Long,
diff --git a/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteEntity.kt b/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteEntity.kt
index d79660a12..95ae66e87 100644
--- a/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteEntity.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteEntity.kt
@@ -21,7 +21,7 @@ import org.koitharu.kotatsu.core.db.entity.MangaEntity
 		)
 	]
 )
-class FavouriteEntity(
+data class FavouriteEntity(
 	@ColumnInfo(name = "manga_id", index = true) val mangaId: Long,
 	@ColumnInfo(name = "category_id", index = true) val categoryId: Long,
 	@ColumnInfo(name = "created_at") val createdAt: Long
diff --git a/app/src/main/java/org/koitharu/kotatsu/history/data/HistoryEntity.kt b/app/src/main/java/org/koitharu/kotatsu/history/data/HistoryEntity.kt
index 181499fa4..4842a36a7 100644
--- a/app/src/main/java/org/koitharu/kotatsu/history/data/HistoryEntity.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/history/data/HistoryEntity.kt
@@ -17,7 +17,7 @@ import org.koitharu.kotatsu.core.db.entity.MangaEntity
 		)
 	]
 )
-class HistoryEntity(
+data class HistoryEntity(
 	@PrimaryKey(autoGenerate = false)
 	@ColumnInfo(name = "manga_id") val mangaId: Long,
 	@ColumnInfo(name = "created_at") val createdAt: Long,
diff --git a/app/src/main/java/org/koitharu/kotatsu/settings/SettingsModule.kt b/app/src/main/java/org/koitharu/kotatsu/settings/SettingsModule.kt
index 230ab0d32..a4fff5d93 100644
--- a/app/src/main/java/org/koitharu/kotatsu/settings/SettingsModule.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/settings/SettingsModule.kt
@@ -5,7 +5,6 @@ import org.koin.android.ext.koin.androidContext
 import org.koin.androidx.viewmodel.dsl.viewModel
 import org.koin.dsl.module
 import org.koitharu.kotatsu.core.backup.BackupRepository
-import org.koitharu.kotatsu.core.backup.RestoreRepository
 import org.koitharu.kotatsu.core.prefs.AppSettings
 import org.koitharu.kotatsu.settings.backup.BackupViewModel
 import org.koitharu.kotatsu.settings.backup.RestoreViewModel
@@ -18,7 +17,6 @@ val settingsModule
 	get() = module {
 
 		factory { BackupRepository(get()) }
-		factory { RestoreRepository(get()) }
 		single(createdAtStart = true) { AppSettings(androidContext()) }
 
 		viewModel { BackupViewModel(get(), androidContext()) }
diff --git a/app/src/main/java/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt b/app/src/main/java/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt
index baa2a5217..52eb86cf0 100644
--- a/app/src/main/java/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt
@@ -6,7 +6,10 @@ import android.app.backup.BackupDataOutput
 import android.app.backup.FullBackupDataOutput
 import android.os.ParcelFileDescriptor
 import kotlinx.coroutines.runBlocking
-import org.koitharu.kotatsu.core.backup.*
+import org.koitharu.kotatsu.core.backup.BackupEntry
+import org.koitharu.kotatsu.core.backup.BackupRepository
+import org.koitharu.kotatsu.core.backup.BackupZipInput
+import org.koitharu.kotatsu.core.backup.BackupZipOutput
 import org.koitharu.kotatsu.core.db.MangaDatabase
 import java.io.*
 
@@ -63,7 +66,7 @@ class AppBackupAgent : BackupAgent() {
 	}
 
 	private fun restoreBackupFile(fd: FileDescriptor, size: Long) {
-		val repository = RestoreRepository(MangaDatabase(applicationContext))
+		val repository = BackupRepository(MangaDatabase(applicationContext))
 		val tempFile = File.createTempFile("backup_", ".tmp")
 		FileInputStream(fd).use { input ->
 			tempFile.outputStream().use { output ->
@@ -73,9 +76,9 @@ class AppBackupAgent : BackupAgent() {
 		val backup = BackupZipInput(tempFile)
 		try {
 			runBlocking {
-				repository.upsertHistory(backup.getEntry(BackupEntry.HISTORY))
-				repository.upsertCategories(backup.getEntry(BackupEntry.CATEGORIES))
-				repository.upsertFavourites(backup.getEntry(BackupEntry.FAVOURITES))
+				repository.restoreHistory(backup.getEntry(BackupEntry.HISTORY))
+				repository.restoreCategories(backup.getEntry(BackupEntry.CATEGORIES))
+				repository.restoreFavourites(backup.getEntry(BackupEntry.FAVOURITES))
 			}
 		} finally {
 			backup.close()
diff --git a/app/src/main/java/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt b/app/src/main/java/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt
index 79f2fc7c4..f63522140 100644
--- a/app/src/main/java/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt
@@ -7,9 +7,9 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.runInterruptible
 import org.koitharu.kotatsu.base.ui.BaseViewModel
 import org.koitharu.kotatsu.core.backup.BackupEntry
+import org.koitharu.kotatsu.core.backup.BackupRepository
 import org.koitharu.kotatsu.core.backup.BackupZipInput
 import org.koitharu.kotatsu.core.backup.CompositeResult
-import org.koitharu.kotatsu.core.backup.RestoreRepository
 import org.koitharu.kotatsu.utils.SingleLiveEvent
 import org.koitharu.kotatsu.utils.progress.Progress
 import java.io.File
@@ -17,7 +17,7 @@ import java.io.FileNotFoundException
 
 class RestoreViewModel(
 	uri: Uri?,
-	private val repository: RestoreRepository,
+	private val repository: BackupRepository,
 	context: Context
 ) : BaseViewModel() {
 
@@ -44,13 +44,13 @@ class RestoreViewModel(
 				val result = CompositeResult()
 
 				progress.value = Progress(0, 3)
-				result += repository.upsertHistory(backup.getEntry(BackupEntry.HISTORY))
+				result += repository.restoreHistory(backup.getEntry(BackupEntry.HISTORY))
 
 				progress.value = Progress(1, 3)
-				result += repository.upsertCategories(backup.getEntry(BackupEntry.CATEGORIES))
+				result += repository.restoreCategories(backup.getEntry(BackupEntry.CATEGORIES))
 
 				progress.value = Progress(2, 3)
-				result += repository.upsertFavourites(backup.getEntry(BackupEntry.FAVOURITES))
+				result += repository.restoreFavourites(backup.getEntry(BackupEntry.FAVOURITES))
 
 				progress.value = Progress(3, 3)
 				onRestoreDone.call(result)
diff --git a/app/src/test/java/org/koitharu/kotatsu/core/backup/JsonSerializerTest.kt b/app/src/test/java/org/koitharu/kotatsu/core/backup/JsonSerializerTest.kt
new file mode 100644
index 000000000..45fda17ec
--- /dev/null
+++ b/app/src/test/java/org/koitharu/kotatsu/core/backup/JsonSerializerTest.kt
@@ -0,0 +1,93 @@
+package org.koitharu.kotatsu.core.backup
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.koitharu.kotatsu.core.db.entity.MangaEntity
+import org.koitharu.kotatsu.core.db.entity.TagEntity
+import org.koitharu.kotatsu.favourites.data.FavouriteCategoryEntity
+import org.koitharu.kotatsu.favourites.data.FavouriteEntity
+import org.koitharu.kotatsu.history.data.HistoryEntity
+import org.koitharu.kotatsu.parsers.model.MangaSource
+import org.koitharu.kotatsu.parsers.model.MangaState
+import org.koitharu.kotatsu.parsers.model.SortOrder
+import java.util.concurrent.TimeUnit
+
+class JsonSerializerTest {
+
+	@Test
+	fun toFavouriteEntity() {
+		val entity = FavouriteEntity(
+			mangaId = 40,
+			categoryId = 20,
+			createdAt = System.currentTimeMillis(),
+		)
+		val json = JsonSerializer(entity).toJson()
+		val result = JsonDeserializer(json).toFavouriteEntity()
+		assertEquals(entity, result)
+	}
+
+	@Test
+	fun toMangaEntity() {
+		val entity = MangaEntity(
+			id = 231,
+			title = "Lorem Ipsum",
+			altTitle = "Lorem Ispum 2",
+			url = "erw",
+			publicUrl = "hthth",
+			rating = 0.78f,
+			isNsfw = true,
+			coverUrl = "5345",
+			largeCoverUrl = null,
+			state = MangaState.FINISHED.name,
+			author = "RERE",
+			source = MangaSource.DUMMY.name,
+		)
+		val json = JsonSerializer(entity).toJson()
+		val result = JsonDeserializer(json).toMangaEntity()
+		assertEquals(entity, result)
+	}
+
+	@Test
+	fun toTagEntity() {
+		val entity = TagEntity(
+			id = 934023534,
+			title = "Adventure",
+			key = "adventure",
+			source = MangaSource.DUMMY.name,
+		)
+		val json = JsonSerializer(entity).toJson()
+		val result = JsonDeserializer(json).toTagEntity()
+		assertEquals(entity, result)
+	}
+
+	@Test
+	fun toHistoryEntity() {
+		val entity = HistoryEntity(
+			mangaId = 304135341,
+			createdAt = System.currentTimeMillis() - TimeUnit.DAYS.toMillis(6),
+			updatedAt = System.currentTimeMillis(),
+			chapterId = 29014843034,
+			page = 35,
+			scroll = 24.0f,
+			percent = 0.6f,
+		)
+		val json = JsonSerializer(entity).toJson()
+		val result = JsonDeserializer(json).toHistoryEntity()
+		assertEquals(entity, result)
+	}
+
+	@Test
+	fun toFavouriteCategoryEntity() {
+		val entity = FavouriteCategoryEntity(
+			categoryId = 142,
+			createdAt = System.currentTimeMillis(),
+			sortKey = 14,
+			title = "Read later",
+			order = SortOrder.RATING.name,
+			track = false,
+		)
+		val json = JsonSerializer(entity).toJson()
+		val result = JsonDeserializer(json).toFavouriteCategoryEntity()
+		assertEquals(entity, result)
+	}
+}
\ No newline at end of file