Convert JSON to Dart online, free. JSON is the dominant data-interchange format for web APIs and config. Null-safe Dart classes model data for Flutter apps and Dart services. JSON to Dart conversion parses your JSON against the ECMA-404 / RFC 8259 grammar (https://www.rfc-editor.org/rfc/rfc8259), builds an in-memory model of its keys, nested objects and arrays, then emits ready-to-use Dart types following the Dart language tour conventions. Processing runs in your browser in JavaScript with no upload or server round-trip — no size limit beyond your device's memory, so multi-megabyte documents convert in milliseconds and sensitive payloads never leave your machine. Typical uses include Flutter mobile apps, Dart backends and JSON model classes.
It maps the full structure of your JSON onto idiomatic Dart types, following the Dart language tour conventions. 100% free, no registration, and complete privacy — everything runs locally in your browser, so your data never touches a server.
Paste JSON and generate Dart types from Dart immediately. Conversion runs client-side, so there is no upload wait and large documents stay fast.
Nested JSON objects, tables and arrays are mapped faithfully onto Dart, including nested types and optional fields.
Your JSON never leaves your device — everything is processed locally in JavaScript, with nothing logged or stored.
Unlimited conversions with no account, no quotas, and no watermark. Works on desktop and mobile.
A JSON document and its Dart equivalent:
JSON input:
{
"title": "Dune",
"pages": 412,
"available": true
}Output:
class Book {
final String title;
final int pages;
final bool available;
Book({required this.title, required this.pages, required this.available});
}Paste your JSON into the editor and press "Convert to Dart". The tool parses it against the ECMA-404 / RFC 8259 grammar, then generates Dart types following Dart language tour conventions — instantly and entirely in your browser. You can validate or format the JSON first to be sure it is clean.
JSON already uses objects, arrays and typed scalars, so mapping to Dart is close to one-to-one: objects become types or structs, arrays become lists, and numbers, booleans and null keep their types.
Optional or nullable members in the generated Dart are inferred from keys missing in some records of your JSON, following Dart language tour. Include the optional fields in your sample so they are typed correctly.
JSON (JavaScript Object Notation) (JSON) — JSON is the dominant data-interchange format for web APIs and config. Dart classes (Dart) — Null-safe Dart classes model data for Flutter apps and Dart services. This converter maps the structure of your JSON onto Dart so you can use it for Flutter mobile apps.
Yes. Invalid JSON is flagged with a clear error before anything is converted. Common JSON problems to check are matched braces and brackets, double-quoted keys, and no trailing commas. Starting from clean input keeps the generated Dart accurate.
Yes. The entire JSON-to-Dart conversion runs locally in your browser in JavaScript — your JSON is never uploaded, logged or stored. That matters when the data is something like REST/GraphQL API payloads, which should not leave your machine.
The generated Dart is ready for Flutter mobile apps, Dart backends and JSON model classes. Copy or download it and drop it straight into your codebase.
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