JSON to Dart Converter
Generate Flutter-ready Dart models with working fromJson and toJson methods, not just field declarations.
Your data stays on your device
Input — JSON
- characters
- 0
- lines
- 0
- size
- 0 B
Output — Dart
- characters
- 0
- lines
- 0
- size
- 0 B
Options
About this tool
Dart has no built-in reflection-based JSON decoding, so every model needs explicit serialisation code. Most projects either write it by hand or run a code generator as a build step; for a single response, generating it here is faster.
The output is null-safe Dart: nullable types where the sample allows null, final fields, and fromJson factories that handle nested objects and lists by delegating to the generated child classes.
How to use this tool
- Paste your JSON sample.
- Set the root class name.
- Choose whether to generate toJson alongside fromJson, and pick a naming convention.
- Press Generate and copy the classes into your Flutter project.
Key features
- fromJson factory constructor for every generated class
- Optional toJson method for round-tripping
- Null-safe types with ? only where the sample requires it
- final fields and a const constructor where possible
- Nested objects and lists decoded through their own generated classes
- Dart reserved words renamed safely
Example
Input — JSON
{"id":2,"title":"Note"}Output — Dart
class Root {
final int id;
final String title;
const Root({required this.id, required this.title});
factory Root.fromJson(Map<String, dynamic> json) => Root(
id: json['id'] as int,
title: json['title'] as String,
);
}Good to know
- The generated fromJson assumes well-formed input; it does not validate or coerce unexpected types.
- Deeply nested list-of-list structures produce verbose decoding expressions.
- No json_serializable annotations are emitted — the code is plain Dart with no build_runner step required.
Frequently asked questions
Why not use json_serializable?
It is an excellent choice for a large project, but it requires build_runner and a generation step. Plain generated code is immediately usable and easier to inspect.
Is the output null-safe?
Yes. It targets modern Dart with sound null safety, and nullable types are used only where the sample shows null or a missing key.
How are nested lists of objects handled?
With a map over the raw list that calls the child class fromJson for each element, then a toList() call.
Do I get equality and hashCode?
Not by default, since that is a design decision. Add a package such as equatable, or override the operators yourself if you need value equality.
Your data stays on your device
Your data is processed locally in your browser and is not uploaded to our server. This page keeps working after you go offline, because there is nothing to send.