JSON Swiss

JSON Swiss

JSON To Dart Generator

Need to convert Dart into JSON Schema?

Dart → JSON Schema

JSON Input

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Generated Dart

Configuration

Enter JSON data to generate Dart classes

Classes with null safety and JSON serialization

How to convert JSON to Dart – step-by-step guide

Use this JSON to Dart generator to create null-safe Dart classes from JSON samples for Flutter apps and Dart services.

  1. Step 1 – Paste a JSON sample

    • Paste a representative JSON object or array into the left editor.
    • Include nested objects, arrays, and nullable fields so types are inferred correctly.
    • Use Import to load JSON from a file, URL, or sample data.

  2. Step 2 – Choose Dart class options

    • Set Class Name for the root model (for example Root).
    • Enable null safety and confirm how optional fields are represented (String?).
    • If you use code generation, choose a serialization style (like json_serializable).

  3. Step 3 – Review the generated code

    • Check field names, types, and how arrays/objects are modeled.
    • Adjust options like Root Type Name, null handling, and frameworks if available.
    • If a field is inferred incorrectly, tweak your sample JSON and regenerate.

  4. Step 4 – Use the models in Flutter/Dart

    • Add the generated classes to your project (for example under lib/models).
    • Parse JSON into models with a fromJson factory or generated serializers.
    • Run flutter format to keep output consistent with your project style.

  5. Step 5 – Copy or download

    • Copy the output into your project or download it as a file.
    • Run your formatter/linter to match your code style.
    • Add JSON parsing/serialization libraries if your language requires them.

Quick tips

  • Keep model classes small and compose nested types for clarity.
  • Use DateTime parsing only when your API format is consistent.
  • Prefer generated serializers for large models to reduce manual mapping bugs.
Example output (simplified)
// JSON input
{
  "id": 123,
  "name": "Maeve Winters",
  "email": "maeve@example.com",
  "active": true,
  "roles": ["admin", "editor"],
  "metadata": { "plan": "pro" },
  "createdAt": "2024-03-01T10:15:00Z",
  "score": 99.5,
  "notes": null
}

// Generated Dart models (simplified)
class Metadata {
  final String plan;
  const Metadata({required this.plan});
}

class Root {
  final int id;
  final String name;
  final String? email;
  final bool active;
  final List<String> roles;
  final Metadata metadata;
  final String createdAt;
  final double score;
  final Object? notes;

  const Root({
    required this.id,
    required this.name,
    required this.email,
    required this.active,
    required this.roles,
    required this.metadata,
    required this.createdAt,
    required this.score,
    required this.notes,
  });
}

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JSON Schema Generator

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JSON Formatter & Validator

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JSON to TypeScript Generator

Generate TypeScript types for shared API contracts across platforms.

Frequently Asked Questions

What Dart features are supported?

The generator creates Dart classes with proper type safety, supports both manual JSON serialization and json_annotation package, uses nullable types for null values, and follows Dart naming conventions.

How does json_annotation work?

When json_annotation framework is selected, generated classes use @JsonSerializable() annotation and generate fromJson/toJson methods automatically with build_runner. This provides type-safe JSON serialization.

How are nullable values handled?

Null values in JSON are mapped to nullable types (?) in Dart, providing null safety. Required fields use 'required' keyword in constructors, following Dart's null safety principles.

What about Dart's type system?

Generated Dart code leverages Dart's strong type system with appropriate types (int, double, String, bool, List, Map) and follows Dart conventions like camelCase for field names.

JSON to Dart Class Generator Online | JSONSwiss