Hide output modes and settings.
dartjson.com
Send feedback about dartjson.com. Copy a link to this JSON and the current settings.
{ }input.json
Copy JSON input to clipboard. Replace JSON input with clipboard text. Remove all JSON input. Load the default example JSON.
● Valid JSON14 lines
Dorder.dart
Copy generated Dart code to clipboard. Hide generated class list. 
import 'package:json_annotation/json_annotation.dart';
part 'order.g.dart';

@JsonSerializable(explicitToJson: true)
class Order {
    @JsonKey(name: "order_id")
  final String orderId;
  final Customer customer;
  final double total;
    @JsonKey(name: "created_at")
  final DateTime createdAt;
  final List<Item> items;

  const Order({
    required this.orderId,
    required this.customer,
    required this.total,
    required this.createdAt,
    required this.items,
  });

  factory Order.fromJson(Map<String, dynamic> json) => _$OrderFromJson(json);
  Map<String, dynamic> toJson() => _$OrderToJson(this);
}

@JsonSerializable(explicitToJson: true)
class Customer {
    @JsonKey(name: "first_name")
  final String firstName;
  final String email;
    @JsonKey(name: "is_verified")
  final bool isVerified;

  const Customer({
    required this.firstName,
    required this.email,
    required this.isVerified,
  });

  factory Customer.fromJson(Map<String, dynamic> json) => _$CustomerFromJson(json);
  Map<String, dynamic> toJson() => _$CustomerToJson(this);
}

@JsonSerializable(explicitToJson: true)
class Item {
  final String sku;
  final int quantity;
  final double price;
  final String? note;

  const Item({
    required this.sku,
    required this.quantity,
    required this.price,
    this.note,
  });

  factory Item.fromJson(Map<String, dynamic> json) => _$ItemFromJson(json);
  Map<String, dynamic> toJson() => _$ItemToJson(this);
}
● Ready to copy60 lines

Convert JSON to json_serializable

Paste a JSON object to generate annotated Dart classes. Save the result using the filename shown above the output, then run build_runner to generate the matching .g.dart part.

Output behavior

Each inferred object gets @JsonSerializable(explicitToJson: true), a const constructor, and fromJson and toJson methods linked to generated functions. @JsonKey(name: ...) preserves source keys such as snake_case while Dart fields use camelCase. Nested models serialize through their own toJson methods.

Project setup

flutter pub add json_annotation
flutter pub add --dev json_serializable build_runner
dart run build_runner build

Before using it

The copied file depends on its generated .g.dart part. Run build_runner again whenever you edit annotated fields or rename the source file; the part directive must match that filename.