diff --git a/api/packages/game_domain/build.yaml b/api/packages/game_domain/build.yaml
new file mode 100644
index 000000000..aaa6e0dd2
--- /dev/null
+++ b/api/packages/game_domain/build.yaml
@@ -0,0 +1,6 @@
+targets:
+  $default:
+    builders:
+      json_serializable:
+        options:
+          explicit_to_json: true
\ No newline at end of file
diff --git a/api/packages/game_domain/lib/src/models/board_section.dart b/api/packages/game_domain/lib/src/models/board_section.dart
new file mode 100644
index 000000000..2580fcf1d
--- /dev/null
+++ b/api/packages/game_domain/lib/src/models/board_section.dart
@@ -0,0 +1,58 @@
+import 'package:equatable/equatable.dart';
+import 'package:game_domain/game_domain.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'board_section.g.dart';
+
+/// {@template board_section}
+/// A model that represents a board section with all the words that
+/// it contains.
+/// {@endtemplate}
+@JsonSerializable(ignoreUnannotated: true)
+class BoardSection extends Equatable {
+  /// {@macro board_section}
+  const BoardSection({
+    required this.id,
+    required this.position,
+    required this.width,
+    required this.height,
+    required this.words,
+  });
+
+  /// {@macro board_section}
+  factory BoardSection.fromJson(Map<String, dynamic> json) =>
+      _$BoardSectionFromJson(json);
+
+  /// Unique identifier of board section.
+  @JsonKey()
+  final String id;
+
+  /// Position of the board section in the board. The origin is the top left.
+  @JsonKey()
+  @PointConverter()
+  final Point<int> position;
+
+  /// Width of the board section.
+  @JsonKey()
+  final int width;
+
+  /// Height of the board section.
+  @JsonKey()
+  final int height;
+
+  /// The words that are contained in this board section.
+  @JsonKey()
+  final List<Word> words;
+
+  /// Returns a json representation from this instance.
+  Map<String, dynamic> toJson() => _$BoardSectionToJson(this);
+
+  @override
+  List<Object?> get props => [
+        id,
+        position,
+        width,
+        height,
+        words,
+      ];
+}
diff --git a/api/packages/game_domain/lib/src/models/board_section.g.dart b/api/packages/game_domain/lib/src/models/board_section.g.dart
new file mode 100644
index 000000000..6852544d9
--- /dev/null
+++ b/api/packages/game_domain/lib/src/models/board_section.g.dart
@@ -0,0 +1,27 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'board_section.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+BoardSection _$BoardSectionFromJson(Map<String, dynamic> json) => BoardSection(
+      id: json['id'] as String,
+      position: const PointConverter()
+          .fromJson(json['position'] as Map<String, dynamic>),
+      width: json['width'] as int,
+      height: json['height'] as int,
+      words: (json['words'] as List<dynamic>)
+          .map((e) => Word.fromJson(e as Map<String, dynamic>))
+          .toList(),
+    );
+
+Map<String, dynamic> _$BoardSectionToJson(BoardSection instance) =>
+    <String, dynamic>{
+      'id': instance.id,
+      'position': const PointConverter().toJson(instance.position),
+      'width': instance.width,
+      'height': instance.height,
+      'words': instance.words.map((e) => e.toJson()).toList(),
+    };
diff --git a/api/packages/game_domain/lib/src/models/models.dart b/api/packages/game_domain/lib/src/models/models.dart
index 4c1c38f2b..a2478f4d4 100644
--- a/api/packages/game_domain/lib/src/models/models.dart
+++ b/api/packages/game_domain/lib/src/models/models.dart
@@ -1 +1,6 @@
+export 'dart:math' show Point;
+
+export 'board_section.dart';
 export 'leaderboard_player.dart';
+export 'point_converter.dart';
+export 'word.dart';
diff --git a/api/packages/game_domain/lib/src/models/point_converter.dart b/api/packages/game_domain/lib/src/models/point_converter.dart
new file mode 100644
index 000000000..b201d51e6
--- /dev/null
+++ b/api/packages/game_domain/lib/src/models/point_converter.dart
@@ -0,0 +1,26 @@
+import 'package:game_domain/game_domain.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+/// {@template point_converter}
+/// A converter that converts a [Point] to a [Map] and vice versa.
+/// {@endtemplate}
+class PointConverter extends JsonConverter<Point<int>, Map<String, dynamic>> {
+  /// {@macro point_converter}
+  const PointConverter();
+
+  @override
+  Point<int> fromJson(Map<String, dynamic> json) {
+    return Point<int>(
+      json['x'] as int,
+      json['y'] as int,
+    );
+  }
+
+  @override
+  Map<String, dynamic> toJson(Point<int> object) {
+    return {
+      'x': object.x,
+      'y': object.y,
+    };
+  }
+}
diff --git a/api/packages/game_domain/lib/src/models/word.dart b/api/packages/game_domain/lib/src/models/word.dart
new file mode 100644
index 000000000..08e56a349
--- /dev/null
+++ b/api/packages/game_domain/lib/src/models/word.dart
@@ -0,0 +1,71 @@
+import 'package:equatable/equatable.dart';
+import 'package:game_domain/game_domain.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'word.g.dart';
+
+/// {@template word}
+/// A model that represents a word in the crossword.
+/// {@endtemplate}
+@JsonSerializable(ignoreUnannotated: true)
+class Word extends Equatable {
+  /// {@macro word}
+  const Word({
+    required this.id,
+    required this.position,
+    required this.answer,
+    required this.clue,
+    required this.hints,
+    required this.visible,
+    required this.solvedTimestamp,
+  });
+
+  /// {@macro word}
+  factory Word.fromJson(Map<String, dynamic> json) => _$WordFromJson(json);
+
+  /// Unique identifier of the word.
+  @JsonKey()
+  final String id;
+
+  /// Position of the board section in the board. The origin is the top left.
+  @JsonKey()
+  @PointConverter()
+  final Point<int> position;
+
+  /// The word answer to display in the crossword when solved.
+  @JsonKey()
+  final String answer;
+
+  /// The clue to show users when guessing for the first time.
+  @JsonKey()
+  final String clue;
+
+  /// The hints to show users when asked for more hints.
+  @JsonKey()
+  final List<String> hints;
+
+  /// Whether the word should be visible or not in the board. Independent of
+  /// the word being solved or not.
+  /// Every solved word is visible, but not every visible word is solved.
+  @JsonKey()
+  final bool visible;
+
+  /// The timestamp when the word was solved. In milliseconds since epoch.
+  /// If the word is not solved, this value is null.
+  @JsonKey()
+  final int? solvedTimestamp;
+
+  /// Returns a json representation from this instance.
+  Map<String, dynamic> toJson() => _$WordToJson(this);
+
+  @override
+  List<Object?> get props => [
+        id,
+        position,
+        answer,
+        clue,
+        hints,
+        visible,
+        solvedTimestamp,
+      ];
+}
diff --git a/api/packages/game_domain/lib/src/models/word.g.dart b/api/packages/game_domain/lib/src/models/word.g.dart
new file mode 100644
index 000000000..4ad00c40b
--- /dev/null
+++ b/api/packages/game_domain/lib/src/models/word.g.dart
@@ -0,0 +1,28 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'word.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+Word _$WordFromJson(Map<String, dynamic> json) => Word(
+      id: json['id'] as String,
+      position: const PointConverter()
+          .fromJson(json['position'] as Map<String, dynamic>),
+      answer: json['answer'] as String,
+      clue: json['clue'] as String,
+      hints: (json['hints'] as List<dynamic>).map((e) => e as String).toList(),
+      visible: json['visible'] as bool,
+      solvedTimestamp: json['solvedTimestamp'] as int?,
+    );
+
+Map<String, dynamic> _$WordToJson(Word instance) => <String, dynamic>{
+      'id': instance.id,
+      'position': const PointConverter().toJson(instance.position),
+      'answer': instance.answer,
+      'clue': instance.clue,
+      'hints': instance.hints,
+      'visible': instance.visible,
+      'solvedTimestamp': instance.solvedTimestamp,
+    };
diff --git a/api/packages/game_domain/pubspec.yaml b/api/packages/game_domain/pubspec.yaml
index 78f90dce0..469d61499 100644
--- a/api/packages/game_domain/pubspec.yaml
+++ b/api/packages/game_domain/pubspec.yaml
@@ -6,12 +6,13 @@ publish_to: none
 environment:
   sdk: ">=3.0.0 <4.0.0"
 
+dependencies:
+  equatable: ^2.0.5
+  json_annotation: ^4.8.1
+
 dev_dependencies:
   build_runner: ^2.4.8
-  mocktail: ^1.0.0
+  json_serializable: ^6.7.1
+  mocktail: ^1.0.3
   test: ^1.19.2
-  very_good_analysis: ^5.1.0
-
-dependencies:
-  equatable: ^2.0.5
-  json_annotation: ^4.8.1
\ No newline at end of file
+  very_good_analysis: ^5.1.0
\ No newline at end of file
diff --git a/api/packages/game_domain/test/src/models/board_section_test.dart b/api/packages/game_domain/test/src/models/board_section_test.dart
new file mode 100644
index 000000000..9ddd1a6e6
--- /dev/null
+++ b/api/packages/game_domain/test/src/models/board_section_test.dart
@@ -0,0 +1,113 @@
+// ignore_for_file: prefer_const_constructors
+// ignore_for_file: prefer_const_literals_to_create_immutables
+
+import 'package:game_domain/game_domain.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('BoardSection', () {
+    test('creates correct json object from BoardSection object', () {
+      final boardSection = BoardSection(
+        id: 'id',
+        position: Point(1, 2),
+        width: 3,
+        height: 4,
+        words: [
+          Word(
+            id: 'id',
+            position: Point(1, 2),
+            answer: 'answer',
+            clue: 'clue',
+            hints: ['hints'],
+            visible: false,
+            solvedTimestamp: 1234,
+          ),
+        ],
+      );
+      final json = boardSection.toJson();
+
+      expect(
+        json,
+        equals({
+          'id': 'id',
+          'position': {'x': 1, 'y': 2},
+          'width': 3,
+          'height': 4,
+          'words': [
+            {
+              'id': 'id',
+              'position': {'x': 1, 'y': 2},
+              'answer': 'answer',
+              'clue': 'clue',
+              'hints': ['hints'],
+              'visible': false,
+              'solvedTimestamp': 1234,
+            },
+          ],
+        }),
+      );
+    });
+
+    test('creates correct BoardSection object from json object', () {
+      final json = {
+        'id': 'id',
+        'position': {'x': 1, 'y': 2},
+        'width': 3,
+        'height': 4,
+        'words': [
+          {
+            'id': 'id',
+            'position': {'x': 1, 'y': 2},
+            'answer': 'answer',
+            'clue': 'clue',
+            'hints': ['hints'],
+            'visible': false,
+            'solvedTimestamp': 1234,
+          },
+        ],
+      };
+      final boardSection = BoardSection.fromJson(json);
+      expect(
+        boardSection,
+        equals(
+          BoardSection(
+            id: 'id',
+            position: Point(1, 2),
+            width: 3,
+            height: 4,
+            words: [
+              Word(
+                id: 'id',
+                position: Point(1, 2),
+                answer: 'answer',
+                clue: 'clue',
+                hints: ['hints'],
+                visible: false,
+                solvedTimestamp: 1234,
+              ),
+            ],
+          ),
+        ),
+      );
+    });
+
+    test('supports equality', () {
+      final firstBoardSection = BoardSection(
+        id: 'id',
+        position: Point(1, 2),
+        width: 3,
+        height: 4,
+        words: [],
+      );
+      final secondBoardSection = BoardSection(
+        id: 'id',
+        position: Point(1, 2),
+        width: 3,
+        height: 4,
+        words: [],
+      );
+
+      expect(firstBoardSection, equals(secondBoardSection));
+    });
+  });
+}
diff --git a/api/packages/game_domain/test/src/models/point_converter_test.dart b/api/packages/game_domain/test/src/models/point_converter_test.dart
new file mode 100644
index 000000000..58ebd3500
--- /dev/null
+++ b/api/packages/game_domain/test/src/models/point_converter_test.dart
@@ -0,0 +1,20 @@
+// ignore_for_file: prefer_const_constructors
+
+import 'package:game_domain/game_domain.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('PointConverter', () {
+    test('creates correct json object from Point object', () {
+      final point = Point(1, 2);
+      final json = PointConverter().toJson(point);
+      expect(json, equals({'x': 1, 'y': 2}));
+    });
+
+    test('creates correct Point object from json object', () {
+      final json = {'x': 1, 'y': 2};
+      final point = PointConverter().fromJson(json);
+      expect(point, equals(Point(1, 2)));
+    });
+  });
+}
diff --git a/api/packages/game_domain/test/src/models/word_test.dart b/api/packages/game_domain/test/src/models/word_test.dart
new file mode 100644
index 000000000..f1dfbe182
--- /dev/null
+++ b/api/packages/game_domain/test/src/models/word_test.dart
@@ -0,0 +1,83 @@
+// ignore_for_file: prefer_const_constructors
+
+import 'package:game_domain/game_domain.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('Word', () {
+    test('creates correct json object from Word object', () {
+      final word = Word(
+        id: 'id',
+        position: Point(1, 2),
+        answer: 'test',
+        clue: 'clue',
+        hints: const ['hint'],
+        visible: true,
+        solvedTimestamp: 0,
+      );
+      final json = word.toJson();
+
+      expect(
+        json,
+        equals({
+          'id': 'id',
+          'position': {'x': 1, 'y': 2},
+          'answer': 'test',
+          'clue': 'clue',
+          'hints': ['hint'],
+          'visible': true,
+          'solvedTimestamp': 0,
+        }),
+      );
+    });
+
+    test('creates correct Word object from json object', () {
+      final json = {
+        'id': 'id',
+        'position': {'x': 1, 'y': 2},
+        'answer': 'test',
+        'clue': 'clue',
+        'hints': ['hint'],
+        'visible': true,
+      };
+      final word = Word.fromJson(json);
+      expect(
+        word,
+        equals(
+          Word(
+            id: 'id',
+            position: Point(1, 2),
+            answer: 'test',
+            clue: 'clue',
+            hints: const ['hint'],
+            visible: true,
+            solvedTimestamp: null,
+          ),
+        ),
+      );
+    });
+
+    test('supports equality', () {
+      final firstWord = Word(
+        id: 'id',
+        position: Point(1, 2),
+        answer: 'test',
+        clue: 'clue',
+        hints: const ['hint'],
+        visible: true,
+        solvedTimestamp: 0,
+      );
+      final secondWord = Word(
+        id: 'id',
+        position: Point(1, 2),
+        answer: 'test',
+        clue: 'clue',
+        hints: const ['hint'],
+        visible: true,
+        solvedTimestamp: 0,
+      );
+
+      expect(firstWord, equals(secondWord));
+    });
+  });
+}