Dev Brains AI
DevBrainsAI

Free JSON to TypeScript Converter

Paste example JSON below and get matching TypeScript interfaces — nested objects become their own named interfaces, arrays become Type[]. Runs entirely in your browser; nothing is uploaded.

Examples
No result yet — press Generate Interfaces.

About the JSON to TypeScript Converter

Hand-writing TypeScript interfaces to match an API response or config file is tedious and error-prone — it's easy to miss a nested field or get an array type wrong. This tool infers the shape directly from real example data: paste JSON, and every nested object becomes its own named interface (so customer gets a Customer interface, not an inline blob), arrays become Type[], and property names that aren't valid TypeScript identifiers are automatically quoted.

Want to pretty-print or validate the JSON first? Use the JSON Formatter. Comparing two JSON payloads instead? Try the JSON Diff Viewer. Need a formal JSON Schema instead of TypeScript types? Use the JSON Schema Generator.

A Note on Arrays

Real-world API arrays don't always have perfectly consistent objects — some items might have an extra optional field. This tool uses the first element of an array as the representative shape, so a field that only appears on the second or third item won't show up in the generated interface. For anything you're about to ship, double check the output against a few different example items, not just one.

FAQ

Is this JSON to TypeScript converter free?
Yes — completely free, with no signup required and no limit on how many times you use it.
How does it handle arrays of objects?
It uses the first element of the array as the representative shape for the generated interface. If your array's objects vary — some have an extra optional field, for example — that field won't be captured. Review the output against your actual data and add optional fields (key?: type) by hand if needed.
What happens to keys that aren’t valid TypeScript identifiers?
Keys with spaces, hyphens, or other characters that would be invalid as bare property names (like "user-id" or "full name") are automatically quoted in the output, e.g. "user-id": number;, which is valid TypeScript.
Is my JSON sent to a server?
No. The entire type inference runs in your browser with JavaScript. Nothing you paste is uploaded, logged, or stored.

More developer tools from Dev Brains AI

Pretty-print or validate JSON with the JSON Formatter, compare two JSON payloads with the JSON Diff Viewer, or generate a formal schema with the JSON Schema Generator.

JSON guides and tutorials