JSON → TypeScript Interface

Paste JSON to auto-generate TypeScript interfaces. Splits nested objects into separate interfaces, infers union types for arrays, optional null / readonly, custom root type name.

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Input JSON

Root type name interface type null becomes optional (?) readonly Inline nested objects export

TypeScript output ⬇ types.ts

❓ FAQ

Mixed array types?

All elements analyzed -> union type (string | number etc.)

null vs undefined?

JSON has no undefined. With option ON: field?: T. With OFF: field: T | null

Date / custom types?

In JSON they're strings, indistinguishable from Date. Manually rewrite afterwards

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JSON → TypeScript Interface

❓ FAQ

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