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JSON to Dart Class Generator

JSON to Dart Object | Generate Flutter Data Classes | Toolkk

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JSON to Dart Class Generator

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TypeScript JavaScript Python Java Go C#Rust Kotlin Swift Dart

TypeScriptJavaScriptPythonJavaGoC#RustKotlinSwiftDartPHPRubyC++Objective-CElmHaskellJSON SchemacJSONElixirCrystalFlowJavaScript PropTypesPikeScala 3SmithyTypeScript Effect SchemaTypeScript ZodMore

JSON Input

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

Dart Options

Type Name

Null Safety

Dart Output

JSON Input

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

Dart Options

Type Name

Null Safety

Just Type Definitions

Use Freezed

Dart Output

JSON to Dart Class Generator

Automatically convert JSON data into Dart data models for Flutter and Dart development. Supports null safety and nested structures.

TypeScript JavaScript Python Java Go C#Rust Kotlin Swift Dart

TypeScriptJavaScriptPythonJavaGoC#RustKotlinSwiftDartPHPRubyC++Objective-CElmHaskellJSON SchemacJSONElixirCrystalFlowJavaScript PropTypesPikeScala 3SmithyTypeScript Effect SchemaTypeScript ZodMore

JSON Input

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

Dart Options

Type Name

Null Safety

Dart Output

JSON Input

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "email": "john.doe@example.com",
  "tags": ["developer", "typescript"],
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "zipCode": "10001"
  },
  "projects": [
    {
      "id": 1,
      "title": "Project Alpha",
      "status": "completed"
    }
  ]
}

Dart Options

Type Name

Null Safety

Just Type Definitions

Use Freezed

Dart Output

Overview

Features and technical background

Understand what the tool solves, how it works, and the boundaries of its data.

Tags: JSON Dart Code Generator Flutter

Turn a JSON sample into a Dart model starting point

Paste valid JSON to generate Dart declarations inferred from its shape. JSON objects become fields, arrays suggest collection types, and nested objects can become additional model types. The sample is evidence about possible values, not a complete API contract: a field that appears non-null in one response may be absent or null in another.

The output is generated from one sample. You can set the root type name and adjust available generation options, including Dart options such as null safety, Freezed, Hive, JSON annotations, final properties, and copyWith. The default settings are language-specific. Dart’s JSON guidance describes serialization and deserialization as converting between JSON data and Dart objects; the generated code still needs to fit the packages and conventions in your project.

Guide

How to use this tool

Follow the workflow and verify inputs and outputs with practical examples.

From sample response to code you can review

Paste a representative JSON value
Use a valid object or array that includes realistic examples of optional, nullable, nested, and repeated fields. The tool reports an error when the JSON cannot be parsed.
Name the root type
Set the type name that represents the top-level structure. Keep it consistent with your application’s naming conventions.
Choose generation options
Open the advanced settings to review shared inference settings and the available Dart-specific choices. Enable annotations or Freezed only if your project has the matching dependencies and build setup.
Inspect, copy, and integrate
Review inferred property types and nested classes against the real API schema. Then copy or download the code and compile it within your project, adding any imports and package configuration it requires.

A sample with a string name, integer identifier, Boolean flag, and nested address can suggest corresponding Dart fields and a nested type. If a second API response allows the identifier to be missing or changes its representation, include that case in your sample or revise the generated type by hand.

Use cases

Where this tool helps

See how the tool fits into real work and everyday tasks.

Where sample-based models help

Scaffold a new API model

Use a representative response to create an initial model, then compare every inferred field with the API documentation before relying on it.

Explore unfamiliar nested data

Generate a readable first pass from a nested response to see its object and list structure. Treat the output as a review aid when mapping unfamiliar payloads.

Match an existing Dart project

Select generation features that align with packages already configured in the app. A setting that emits annotations or framework-specific code does not add those dependencies to the project.

Q&A

Frequently asked questions

Find concise answers to common questions and confusing cases.

Common Dart generation questions

Does generated Dart code guarantee that an API response is valid?

No. It reflects the values and shape in the sample. Check optional fields, nulls, alternate types, and future response variants against the API contract.

Is null safety always an explicit option?

The generator exposes Dart-specific settings, including null safety, and applies its language defaults. Review the selected setting and the resulting types rather than assuming every generated field should be nullable.

Why does an empty or incomplete array produce a broad type?

A sample with no representative elements provides little evidence about the element type. Add realistic array items and regenerate, or specify the intended type yourself.

Will annotation or Freezed code work immediately?

Only when the project has the corresponding packages and code-generation setup. Generated source does not install dependencies or configure a Dart project.

Notes

Important notes and limitations

Review scope, result limitations, and important precautions before use.

Review inferred types before shipping

Generated declarations are a scaffold. Validate them against the API schema and test them with real responses, especially when fields are optional, nullable, polymorphic, or inconsistent across records.

A single JSON sample cannot establish all valid server responses or business rules.
Check imports, package versions, annotations, serializers, and build steps in the destination project.
Do not paste credentials or private response data into a web tool unless your organization permits that use.

Source: Dart: Using JSON; supports the role of JSON serialization/deserialization and code-generation approaches; checked 2026-09-28.
Source: Dart: Sound null safety; supports the distinction between nullable and non-nullable Dart types; checked 2026-09-28.

Explore related resources

Discover related tools, collections, and available API capabilities.

API service

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JSON InputFormatSample

Dart OptionsShow Advanced

Dart OutputDownload

JSON Input

Dart OptionsMore

Dart Output

JSON InputFormatSample

Dart OptionsShow Advanced

Dart OutputDownload

JSON Input

Dart OptionsMore

Dart Output

Turn a JSON sample into a Dart model starting point

From sample response to code you can review

Paste a representative JSON value

Name the root type

Choose generation options

Inspect, copy, and integrate

Where sample-based models help

Scaffold a new API model

Explore unfamiliar nested data

Match an existing Dart project

Common Dart generation questions

Review inferred types before shipping

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JSON Input

Dart Options

Dart Output

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