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JSON to TypeScript Interface

Paste any JSON and get clean, ready to use TypeScript interfaces with nested objects, arrays, and optional fields inferred automatically.

JSON input

Paste JSON, optionally name the root type, then generate.

Your TypeScript interface code will appear here.
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How type inference works

Paste a JSON payload and click Generate. The tool walks the JSON recursively: objects become interfaces, arrays become typed arrays, and each value becomes string, number, boolean, or a nested interface. Keys that appear only in some array items are marked optional with ?, so the result mirrors real world API responses.

Where to use the output

Use the generated interfaces to type API responses in Angular, React, or Node.js projects. Paste them next to your fetch calls and your editor will autocomplete fields and flag typos at compile time, which removes a whole class of runtime bugs.

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JSON to TS Interface FAQs

What does this tool generate?
It converts your JSON sample into TypeScript interface declarations, one per nested object, with string, number, boolean, array, and null types inferred from the actual values.
How are nested objects handled?
Each nested object becomes its own exported interface named after its key, so address becomes Address and projects becomes Project, keeping the output modular and reusable.
How are optional fields detected?
If a key is missing from some items in an array, or its value is null, the field gets a ? marker, which mirrors how real API responses vary between records.
Do integers and decimals become different types?
No, both map to number, which is the correct TypeScript type for all JSON numbers, since JSON itself does not distinguish integers from decimals.
Is my JSON sent to a server?
No. Parsing and code generation run entirely in your browser, so your JSON never leaves your device.
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