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JSON to TypeScript

Turn a JSON sample into TypeScript interfaces.

Root name: Mark missing keys optional

How to Use

Paste the JSON, for example an API response, into the left box.
TypeScript is already chosen; pick interface or type.
Set the Root name, such as User or ApiResponse.
Copy the interfaces into your project.

Frequently Asked Questions

interface or type?

Both describe the same shape. Interfaces can be extended and merged, type aliases can also express unions; many teams simply pick one style.

Why is a field optional?

It was missing from some items of an array. Turn off Mark missing keys optional to make every field required.

Why is a field typed as unknown?

Its values had different types in the sample, or it was always null. Set the right type by hand.

Is my JSON sent anywhere?

No. The interfaces are generated in your browser.

Generate TypeScript Interfaces from JSON

Updated September 30, 2026 · By Saman

Typing an API response by hand is slow and easy to get wrong. This page opens JSON to Types with TypeScript chosen, so a sample response becomes a set of interfaces in one step.

Example

The sample {"id": 1, "tags": ["a"], "owner": {"name": "Ada"} } gives an Owner interface with name: string and a Root interface with id: number, tags: string[] and owner: Owner.

Related tools

For runtime validation, generate a JSON Schema from the same sample. For a Go backend, see JSON to Go.

Guides

How to Type an API Response in TypeScript fetch gives you data typed as any, which switches TypeScript off exactly where bugs come from. Here is how to give API data a real type, quickly and safely.

JSON to TypeScript

Generate TypeScript Interfaces from JSON

Example

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Guides

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