JSON to TypeScript
TypeScript interfaces define the expected shape of data at compile time, catching type errors before code runs. Generating interfaces from sample JSON is a fast way to bootstrap type definitions when integrating with external APIs or migrating a JavaScript codebase to TypeScript.
1.
Paste JSON into the Input panel
2.
The TypeScript interface is generated instantly, with inferred types for all fields
3.
Copy and paste it into your project
▸
Typing API response objects when building TypeScript applications
▸
Generating interfaces for configuration files or stored data structures
▸
Bootstrapping types from sample data before writing full models
Does it handle nested objects?
Nested objects generate inline object type literals inside the root interface (e.g., address: { street: string; city: string; }), and arrays generate typed array properties (e.g., string[], { id: number; name: string; }[]).
What happens with null values?
Properties with null values are typed as unknown in the generated interface. You will want to update the type to the appropriate union (e.g. string | null) once you know the actual type.
Can I use this with API responses?
Paste the raw JSON response from any API and get TypeScript interfaces you can use immediately in your project.
Is my data sent to a server?
Type generation runs entirely in your browser. No JSON is uploaded or stored.
Does it handle arrays of mixed types?
Mixed-type arrays are typed as a union (e.g. (string | number)[]). For the most accurate types, ensure your sample JSON uses consistent value types within each array.