JSON to Dart.

Pandia turns a JSON document into plain Dart classes with null safety applied. Every class gets a const constructor, final fields, a fromJson factory and a toJson method — so the serialization code you would normally generate with build_runner is already in the output. Nested objects and arrays become their own classes and List<T>.

Example

Input JSON:

{
  "id": 42,
  "name": "Ada",
  "active": true,
  "tags": ["admin", "early"]
}

Dart output:

class Root {
  const Root({
    required this.active,
    required this.id,
    required this.name,
    required this.tags,
  });

  factory Root.fromJson(Map<String, dynamic> json) => Root(
        active: json['active'] as bool,
        id: json['id'] as int,
        name: json['name'] as String,
        tags: List<String>.from(json['tags'] as List<dynamic>),
      );

  final bool active;
  final int id;
  final String name;
  final List<String> tags;

  Map<String, dynamic> toJson() => {
        'active': active,
        'id': id,
        'name': name,
        'tags': tags,
      };
}

What you get

• Null-safe classes with final fields and a const constructor.
• fromJson and toJson included — no json_serializable, no build_runner.
• Optional fields become nullable (?) and drop out of the required parameters.
• Field names become lowerCamelCase while the original JSON keys stay in the maps.

It’s the same engine behind Pandia’s type generation — opinionated, deterministic, and built to run on files far too large for an online converter.

Frequently asked questions

How do I generate Dart classes from JSON?

Open the Types panel in Pandia, choose Dart, and copy the generated classes into your Flutter or Dart project.

Do I need json_serializable or build_runner?

No. Each class carries its own fromJson factory and toJson method, so there is no code generation step and no extra package to add.

Is the output null-safe?

Yes. Fields missing from some objects become nullable and are left out of the required constructor parameters, so the classes compile under Dart null safety.

More converters: JSON to TypeScript · JSON to Go · JSON to Rust · JSON to Python · JSON to Zod · all tools · download.