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{}JSONKits

JSON to Dart Freezed

Generate Dart Freezed data classes with JSON serialization from JSON samples.

Input

json
loading editor…

Paste your JSON here...
or drop a file anywhere in this pane

Output

dart

Generated Freezed class will appear here...
press ⌘↵ to generate freezed

What Is JSON to Dart Freezed?

JSON to Dart Freezed generates immutable Dart data classes with JSON serialization from JSON samples. Freezed is a popular Dart code generator that eliminates boilerplate by creating immutable classes with copyWith, equality overrides, toJson/fromJson, and pattern matching support.

This tool takes a sample JSON object and produces production-ready Freezed data classes that you can drop directly into your Flutter project. It is perfect for:

  • Flutter development: Quickly create model classes for REST API responses without manual typing.
  • Rapid prototyping: Generate complete data layer code from mock API responses in seconds.
  • Consistent patterns: Ensure all team members use the same Freezed conventions with correct @JsonKey annotations and fromJson factories.

How to Convert JSON to Dart Freezed Online

  1. Paste a JSON sample: Copy a JSON object representing your data model and paste it into the editor.
  2. Click Generate Freezed: Press the "Generate Freezed" button to produce the Dart code.
  3. Review the class: Check the generated class properties, JSON annotations, and factory constructors.
  4. Copy to your project: Copy the generated code into your Flutter project's model file and run dart run build_runner build to generate the Freezed implementation.

Frequently Asked Questions

Does the generated Freezed class use @JsonKey annotations for snake_case fields?

Yes. If your JSON keys use snake_case (e.g., first_name), the generator automatically adds @JsonKey(name: 'first_name') annotations so the Dart camelCase properties map correctly during serialization.

Is this tool safe?

Yes. All processing happens 100% client-side in your browser.

Is this tool free?

Yes, completely free with no usage limits.

Real-World Examples

A Flutter mobile developer building a social media app receives a new API specification with 15 JSON endpoints. Instead of hand-writing every model class with Freezed boilerplate, they paste each JSON response into this tool and generate the complete data layer in minutes — saving hours of repetitive coding while ensuring exact alignment with the API contract.

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