JSON to TypeScript Converter - Generate Interfaces Online
Convert JSON to TypeScript interfaces and types instantly — paste any API response, get clean type-safe definitions in one click.
// TypeScript interfaces will appear here
What is a JSON to TypeScript Converter?
A JSON to TypeScript converter is a free online tool that reads a JSON object — such as an API response, configuration file, or database record — and automatically generates matching TypeScript interfaces and types. Instead of writing types by hand, you paste your JSON, click convert, and get type-safe definitions ready to drop into your React, Next.js, Node.js, or Angular project.
Why Convert JSON to TypeScript?
Modern apps consume large, deeply nested JSON payloads. Typing them manually is slow and error-prone. This converter infers the exact shape of your data — including nested objects, arrays, optional fields, and nullable values — so you get accurate, maintainable TypeScript every time.
- Generate TypeScript interfaces instantly
- Type API and GraphQL responses safely
- Auto-detect nested objects and arrays
- Mark optional and nullable properties correctly
- Choose between
interfaceandtype - Improve autocomplete and catch bugs at compile time
Common JSON to TypeScript Use Cases
REST API Types
Turn REST API responses into typed interfaces for fetch calls.
React Props & State
Generate types for component props, hooks, and API data.
Node.js Models
Create request/response models for Express and Nest APIs.
GraphQL Payloads
Type GraphQL query results and mutation responses.
MongoDB Documents
Convert exported MongoDB documents into TypeScript models.
Config Files
Generate strong types for JSON configuration files.
How to Convert JSON to TypeScript
- Paste your JSON into the input box (or upload a .json file).
- Optionally set the root interface name and output style.
- Click Convert to generate TypeScript interfaces.
- Copy the result or download it as a
.tsfile.
Everything You Should Know About TypeScript Types
TypeScript is a strongly typed superset of JavaScript that adds static types on top of plain JS. When you describe the shape of your data with an interface or a type alias, the compiler checks your code against that shape and your editor gives you accurate autocomplete and inline errors.
- Interfaces vs types: interfaces are great for object shapes and can be extended or merged; type aliases can also describe unions, intersections, and primitives.
- Optional properties use
?(e.g.pinned?: boolean) for keys that may be missing. - Nullable values are expressed with unions like
string | null. - Arrays are typed as
string[],number[], orUser[]for arrays of objects. - Nested objects become their own interfaces and are referenced by name for clean, reusable types.
This converter applies all of these rules automatically, so the generated output matches how an experienced TypeScript developer would model the same data.
JSON to TypeScript for Developers
This converter is designed for:
- React & Next.js developers
- Angular developers
- Node.js & NestJS developers
- Full-stack TypeScript engineers
- Frontend developers consuming APIs
- Backend developers defining response models
- QA & automation engineers
🎥 Video Guide
❓ FAQs
What is a JSON to TypeScript converter?
A JSON to TypeScript converter is a tool that reads a JSON object and automatically generates matching TypeScript interfaces and types, so you get type-safe definitions without writing them by hand.
How do I convert JSON to TypeScript?
Paste your JSON into the input box and click Convert. The tool parses the JSON, infers the type of every field, and generates ready-to-use TypeScript interfaces you can copy into your project.
Is this JSON to TypeScript converter free?
Yes. The converter is completely free to use with no limits, sign-up, or installation required.
Does the converter handle nested objects?
Yes. Nested objects are turned into their own separate interfaces and referenced by name, giving you clean, reusable TypeScript types for deeply nested JSON.
How are arrays converted to TypeScript?
Arrays of primitives become typed arrays like string[] or number[]. Arrays of objects are merged into a single interface and typed as InterfaceName[], so all items share one type.
Can it detect optional properties?
Yes. When converting an array of objects, any key that is missing from some items is marked optional with a ? so your interfaces accurately reflect the data.
Can I choose between interface and type?
Yes. You can switch the output style between TypeScript 'interface' declarations and 'type' aliases, and toggle whether the types are exported.
Is my JSON data secure?
Yes. All conversion happens entirely inside your browser. Your JSON is never uploaded to a server or stored anywhere, so it stays completely private.
What happens with null values?
Fields with null values are typed as null (or unioned with their detected type, e.g. string | null) so you keep accurate nullable typing in TypeScript.
Can I rename the root interface?
Yes. You can set a custom name for the root interface, which is also used to derive sensible names for nested interfaces.
Why use TypeScript interfaces instead of plain JSON?
TypeScript interfaces give you compile-time type checking, autocomplete, and safer refactoring. Generating them from real JSON saves time and avoids mistakes when typing API responses.
Does this work with API responses?
Absolutely. Paste a sample response from any REST or GraphQL API and instantly get TypeScript interfaces for your fetch calls, hooks, and data models.
Can I copy or download the generated TypeScript?
Yes. You can copy the generated interfaces to your clipboard with one click or download them as a .ts file ready to drop into your project.
Can beginners use this tool?
Yes. The interface is simple: paste JSON, click Convert, and copy the result. No TypeScript expertise is needed to generate correct types.
Which browsers support this converter?
The JSON to TypeScript converter works on Chrome, Firefox, Safari, Edge, and all modern browsers with JavaScript support.