JSON → Dart classes

Client

Paste JSON to get immutable classes with required constructor parameters—add fromJson or code generation when you wire json_serializable.

Learn more: JSON and Dart

Emit immutable classes with `final` fields and a required constructor—pair with json_serializable or hand-written fromJson for JSON.

Scope

Reserved Dart identifiers get a `Field` suffix; numbers use double. Flutter and server Dart share the same shape patterns.

JSON → Dart

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Parses JSON in your browser and emits classes inferred from the sample shape. Nested objects become nested types; arrays use the first element only to guess item shape. Nothing is uploaded.

Add fromJson/toJson or json_serializable—this output is shape scaffolding only.

Common use cases

  • Draft immutable classes for Flutter apps or server Dart before wiring json_serializable.
  • Compare API field names with Dart naming conventions and required vs optional parameters.
  • Share a quick model shape in mobile PRs when the backend ships sample JSON.

Common mistakes to avoid

  • Skipping null-safety on fields that can be absent

    Mark nullable types when responses vary; a single happy-path sample may hide nulls.

  • Forgetting Equatable or freezed when you need value equality

    Generated classes are structural; add codegen packages when you rely on equality or unions.

FAQ

Is Dart code generated locally?

Yes. Inference runs in your browser tab.

Does this emit fromJson / toJson?

It focuses on class fields. Add json_serializable or manual mappers for serialization.

More tools

Related utilities you can open in another tab—mostly client-side.