JSON to Dart Model Converter – Flutter Classes Online

Input

Output

Ready

Ln 1, Col 1

Convert JSON to Dart in one step

Paste JSON and get null-safe Dart model classes with fromJson factories and toJson methods, ready to use in Flutter apps without extra packages.

How to use it

Paste a JSON sample into the Input panel, open a file, or drop it onto the page. A sample is already loaded so you can see the result.
The Dart code appears instantly in the Output panel and updates as you type.
Rename the top-level type under Settings → Root type name, and use Sort keys to order fields alphabetically.
Copy the code or Download it as Root.dart.

What the Dart generator produces

Immutable classes with final fields and a const constructor using named parameters.
required for fields present in every sample; nullable types (int?) otherwise.
fromJson handles nested objects, lists of objects and num-to-double conversion.
toJson converts nested models back to maps.

Using the generated Dart code

Parse a response with dart:convert:

import 'dart:convert';

final data = Root.fromJson(jsonDecode(body) as Map<String, dynamic>);
print(data.users.first.name);
final back = jsonEncode(data.toJson());

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JSON to Dart FAQ

Do I need json_serializable or build_runner?

No. The fromJson and toJson code is written out in full, so the models have no dependencies and need no code generation step.

Is my data uploaded to a server?

No. The JSON to Dart runs entirely in your browser using JavaScript. Your data is never uploaded, logged or stored, and the tool keeps working offline after your first visit.