ModelDevKit - JSON to Native App Models

JSON Input

Raw JSON and escaped JSON strings are detected automatically

Template Custom

Paste JSON or a stringified JSON value here...

Example:
{"id":1,"name":"Olivia","isActive":true,"address":{"city":"London"}}

Swift Codable

Waiting

Waiting for valid JSON

Options Overrides

Waiting for valid JSON

How It Works

Three steps. No setup required.

Paste a payload, pick a target language, and leave with production-friendly models in minutes.

{}

Step 1

Paste JSON

Drop in a sample object, array, or full API response from the payload you are working with.

[]

Step 2

Choose output

Switch between Swift, Kotlin, TypeScript, Dart, Java, C#, Python, and Go to match your stack.

Step 3

Copy models

Review smart type suggestions, apply safe decoding options, and copy or download the final code.

Use Cases

Built for the JSON work developers do every week.

From mobile payloads to frontend validation and deeply nested API responses, ModelDevKit is designed for real project workflows.

{}

iOS API models

Generate Swift Codable models with CodingKeys, safer decoding, and better handling for dates, UUIDs, and URLs.

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Android data classes

Turn sample payloads into Kotlin data classes with Kotlinx, Moshi, Gson, or Jackson-friendly output.

TypeScript + Zod

Create interfaces and runtime-safe Zod schemas from the same JSON shape for web apps and API clients.

Flutter models

Generate Dart models with copyWith, Equatable, and json_serializable support for app-ready workflows.

Nested API responses

Break down large REST payloads into shared nested models instead of manually carving out object trees.

Messy real-world payloads

Review enum-like strings, quoted numbers, optional fields, and risky scalar values before they become app bugs.

Features

Everything you need to turn sample JSON into production-friendly models.

Strong type inference, nested model generation, safer decoding, and cross-platform output in one focused tool.

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Batch model generation

Generate the root type plus nested models from a single API response, with shared structures reused instead of duplicated.

Smart type suggestions

Detect likely Date, UUID, URL, quoted integer, quoted boolean, and enum-like values before you lock in stronger native types.

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Field overrides and enum control

Review every field, override inferred scalar types, configure enum cases, and keep naming aligned with your app codebase.

Safe decoding helpers

Use safer native parsing for risky API values in Swift and Kotlinx, with project-level and field-level date format control.

TypeScript and Flutter support

Generate TypeScript interfaces with Zod schemas, Dart models with copyWith and json_serializable output, and Python Pydantic models with optional FastAPI scaffolds.

Python Pydantic and FastAPI

Generate Python Pydantic models with aliases, strict or lenient validation, richer scalar types, and optional FastAPI-ready scaffolds.

Why ModelDevKit

Built for the way developers actually work with JSON.

A clear comparison against the usual alternatives, so you can decide where a focused model generator saves the most time.

Capability	ModelDevKit	Generic converters	Manual modeling
Nested model generation	✓	Partial	✕
Smart type suggestions	✓	Partial	✕
Field overrides and enum control	✓	Partial	✕
TypeScript + Zod and Flutter-ready output	✓	✕	✕
Python Pydantic and FastAPI-ready output	✓	Partial	✕
Safer decoding helpers	✓	✕	✕
Local browser-based generation	✓	Partial	✓

Privacy-first, always.

ModelDevKit runs locally in your browser by default. Your JSON stays on your machine during normal use, and content is only shared if you explicitly include it in feedback.

Local browser processingNo backend requiredNo automatic data collection

FAQ

Common questions.

If you do not see your question, get in touch.

Is my data stored on your servers?

No. Model generation runs locally in your browser, so pasted JSON is not uploaded during normal use. The only time JSON is sent anywhere is if you explicitly include it in a feedback submission.

Does ModelDevKit support my language or framework?

ModelDevKit supports Swift, Kotlin, TypeScript, Dart, Java, C#, Python, and Go. It also includes framework-aware output such as Swift Codable, Kotlinx Serialization, TypeScript with Zod, and Flutter-friendly Dart models.

Can I copy or export the generated models directly?

Yes. You can copy the generated code instantly or download it as model files, including nested and related models generated from the same JSON payload.

Do I need to sign up or pay to use it?

No sign-up is required to use the generator. You can paste JSON and generate models immediately in the browser.

Can it generate nested models from a full API response?

Yes. ModelDevKit can generate the root model along with nested child models, array item models, and reused shared structures from the same JSON response.

Can I change field types or keep certain values as strings?

Yes. You can review inferred fields, override scalar types, configure enums, and keep original strings when that is safer for your API payload.

Does it handle tricky values like Date, UUID, URL, or enums?

Yes. ModelDevKit detects likely smart types and surfaces suggestions for values such as dates, UUIDs, URLs, quoted numbers, quoted booleans, and enum-like fields before you lock in stronger native types.

Still wondering? Request / Feedback