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JSON to TypeScript

Turn a JSON sample into named, typed TypeScript interfaces with nullable and shared shapes handled.

Generate TypeScript interfaces

Generated: —
Nested interfaces take their names from the key path, identical shapes are declared once and null values become union types.

How to use the JSON to TypeScript

  1. Paste a JSON sample and name the root interface you want.
  2. Press Generate interfaces to infer every nested type.
  3. Copy the TypeScript declarations into your project.

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Frequently Asked Questions

Common questions about the free online json to typescript.

Paste a JSON sample, set the root interface name and press Generate interfaces to get typed declarations.
Each nested object takes a PascalCase name built from the key path, so an address inside user becomes UserAddress.
Objects with an identical structure are detected and declared only once, so both fields reuse the same interface.
Values that are null, or keys missing from some array items, become optional fields typed with a union that includes null.
Array items are merged, then emitted as Array of the element type, including arrays of nested objects.
Yes. Keys that are not valid identifiers are emitted as quoted property names so the generated code still compiles.
No. The generator is plain web page JavaScript and runs in any modern browser with no install or build step.
No. Parsing and code generation happen locally in your browser, so your data never leaves your device.
Yes. It is completely free, unlimited and requires no account, sign-up or payment.

Last updated: October 10, 2026