Introducing json2dartgen: Generate Dart Models from JSON Effortlessly 🚀

I’m excited to announce the release of json2dartgen — a brand new CLI tool to make working with JSON in Dart and Flutter projects much easier.

Why json2dartgen?

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If you’ve ever worked with APIs in Flutter, you know the pain: you get a massive JSON response, and now you need Dart models with fromJson, toJson, and maybe a copyWith method too. Tools like quicktype.io are great, but they often struggle with very large JSONs or don’t quite integrate with your code style.

That’s why I built json2dartgen:

• Works directly from the command line
• Handles large JSON files with ease
• Fully supports json_serializable
• Generates clean, idiomatic Dart code

Features

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• ✅ fromJson / toJson using json_serializable
• ✅ Automatic copyWith generation
• ✅ Optional snake_case → camelCase conversion
• ✅ Output models as a single file or multiple files
• ✅ Configurable via CLI flags
• ✅ Lightweight, fast, and built for Dart devs

Installation

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Install globally via Dart:

dart pub global activate json2dartgen

Usage

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json2dartgen <input.json> [options]

Options

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Example

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Input JSON:

{
  "building_id": 1130,
  "floor_count": 5,
  "location_name": "North Wing"
}

Generated Dart model:

import 'package:json_annotation/json_annotation.dart';

part 'root.g.dart';

@JsonSerializable()
class Root {
  @JsonKey(name: 'building_id')
  final int buildingId;

  @JsonKey(name: 'floor_count')
  final int floorCount;

  @JsonKey(name: 'location_name')
  final String locationName;

  const Root({
    required this.buildingId,
    required this.floorCount,
    required this.locationName,
  });

  Root copyWith({
    int? buildingId,
    int? floorCount,
    String? locationName,
  }) {
    return Root(
      buildingId: buildingId ?? this.buildingId,
      floorCount: floorCount ?? this.floorCount,
      locationName: locationName ?? this.locationName,
    );
  }

  factory Root.fromJson(Map<String, dynamic> json) => _$RootFromJson(json);
  Map<String, dynamic> toJson() => _$RootToJson(this);
}

Try It Out

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You can get started right now:

dart pub global activate json2dartgen
json2dartgen your_api_response.json --camel-case --output-dir lib/models

What’s Next?

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This is just the beginning 🚀. Future updates will include:

• More configuration options
• Better error messages
• Improved type inference
• Flutter-specific utilities

If you try it out, I’d love to hear your feedback and feature requests.

👉 Check it out here: json2dartgen on pub.dev

Happy coding! 💙