DollarWise

Free JSON to TypeScript Converter — Generate Interfaces Instantly

October 13, 2026 · 2 min read · By the DollarWise team

Turn any JSON into clean TypeScript interfaces or type aliases — nested objects, arrays, nulls and mixed types all handled automatically. Everything runs locally in your browser, so your API responses and data samples never touch a server.

JSON to TypeScript Converter

Paste JSON, get ready-to-use TypeScript interfaces — nested inference, smart optionals, null-safe. All in your browser.

100% Free Forever No Sign-up No Credit Card Private — files never leave your browser Unlimited Use

1 Paste your JSON

Works with objects, arrays of objects, nested structures — anything valid JSON.

2 Output settings

Nested objects become Root + their key name (e.g. Address).
Smart mode is best for arrays of objects with uneven shapes.
Matches your project's formatting style.
Export keyword
Uncheck for quick playground pastes.

3 Generate & copy

Generating…

⚙️ Generated TypeScript

Paste JSON above and hit Generate — nested objects become their own named interfaces.
🎉 Free forever. No sign-up. No credit card. No limits.

This converter runs entirely in your browser — convert as much JSON as you like, as often as you like.

How it works

Paste valid JSON and the converter walks every value recursively: strings become string, numbers become number, booleans become boolean, and nested objects become their own named interfaces (e.g. an address object becomes interface Address). Arrays of objects are merged into one interface — keys missing from some items get a ?, so uneven API shapes stay accurate. Empty arrays fall back to any[], and keys that aren’t valid identifiers are safely quoted.

Everyday uses

  • Typing API responses: paste a real API payload and get production-ready interfaces instead of hand-writing them.
  • Mocking data: generate the shape first, then build typed mocks and fixtures around it.
  • Migrating to TypeScript: convert sample JSON configs and fixtures during a JS → TS migration.
  • Documenting data shapes: share a generated interface in a PR review so the contract is visible.
  • Learning TypeScript: paste familiar JSON and see exactly how its types map to interface syntax.

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