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JSON to TypeScript Interface Generator

Paste any JSON object or array and this JSON to TypeScript converter instantly generates matching interfaces or type aliases, with nested objects and arrays inferred automatically.

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About the JSON to TypeScript Converter

Writing TypeScript interfaces by hand for a large API response is slow and error-prone. This JSON to TypeScript converter parses your sample data, walks every nested object and array, and generates a typescript type generator output made of clean, dependency-ordered interfaces or type aliases, so the types you paste into your project always compile in the right order.

It infers strings, numbers, booleans, and null values directly from your sample, generates a nested interface for every object it finds, and deduplicates repeated shapes so you never get the same interface defined twice. Arrays are inspected element by element, so a uniform list of objects becomes a single referenced type while a mixed array becomes a proper union.

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How to Use

  1. Paste a JSON object or array into the input field, or click Load sample JSON to try it instantly.
  2. Set a Root Interface Name for the top-level type, and choose whether you want interface or type alias output.
  3. Toggle Use optional properties on if you want every field marked with a ?, useful when your sample data may not always be complete.
  4. Click Generate, then Copy the result or Download .ts to save it as a file.

Why Use This TypeScript Type Generator

Accurate Nested Types

Every nested object gets its own named interface instead of one unreadable inline blob, and repeated shapes are automatically deduplicated.

Smart Array Inference

Arrays of objects, primitives, or mixed values are all inspected element by element, producing unions where the data genuinely varies.

Zero Server Uploads

Your JSON, including any real API response data, never leaves your browser tab while it is converted.

Flexible Output

Choose between interface and typesyntax so the output matches your team's existing style guide.

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Who Should Use This Tool

  • Frontend developers who need to convert an API response to TypeScript before wiring up a fetch call or React component.
  • Full-stack engineers who want a quick json to type online reference while designing a shared request or response contract.
  • Backend teams documenting JSON payloads who want consumer-ready TypeScript interfaces without writing them by hand.
  • Students and learnersexploring how JSON structures map onto TypeScript's type system.

Privacy first. No JSON you paste into this tool is ever uploaded, logged, or stored on a server. Parsing and type generation happen entirely on your device inside your browser tab.

This JSON to TypeScript converter parses your JSON with JSON.parse, walks every object and array, and writes matching interfaces or type aliases. Nested objects become their own named interfaces referenced from the parent, arrays are typed by inspecting their elements, and everything runs locally in your browser without any upload.
Yes, generating a TypeScript interface from JSON with nested objects is exactly what this tool is built for. Every nested object gets its own named interface, PascalCased from the property key it was found under, and referenced from the parent type so the output stays readable instead of one giant inline blob.
Yes, this JSON to type online tool is completely free with no sign-up, watermark, or daily limit. Paste any JSON object or array, generate as many TypeScript interfaces or type aliases as you need, and copy or download the result at no cost.
This typescript type generator inspects every element in an array to infer its type automatically. A uniform array of objects produces a single referenced interface, an empty array becomes unknown[] since no shape can be inferred, and an array mixing types like strings and numbers produces a union such as (string | number)[].
Yes, you can convert an API response to TypeScript by pasting the raw JSON body straight from your network tab or API documentation. The generator infers every nested object and array shape automatically, so you get ready-to-use interfaces for your fetch or axios response without typing them by hand.