JSON to TypeScript Interface Generator
Paste a JSON sample and receive TypeScript interfaces that describe it. Instead of hand-writing types to match an API payload, generate them from a real example and paste them into your project.
Step-by-step guide to the JSON to TypeScript Interface Generator
- Paste a representative JSON object or array into the input area.
- Press generate to derive the interface definition.
- Review the types, including nested interfaces for inner objects.
- Copy the output into your TypeScript project as a starting point.
Practical scenarios for the JSON to TypeScript Interface Generator
- Typing an external API response before writing the calling code.
- Migrating a JavaScript project to TypeScript incrementally.
- Documenting the shape of configuration files for teammates.
- Creating types for test fixtures from recorded payloads.
How the JSON to TypeScript Interface Generator works under the hood
The generator infers each property's TypeScript type from the value it sees: strings, numbers, booleans, null, arrays with union element types when mixed, and nested interfaces for objects. Nested structures become separate named interfaces so the output compiles cleanly. The inference runs locally, which matters when the sample payload comes from a private API or contains seeded data.
What the JSON to TypeScript Interface Generator does not do
Types are inferred from one sample; optional fields, unions across samples, or nullability patterns may need manual adjustment afterward.
Common questions about the JSON to TypeScript Interface Generator
Does it mark fields as optional?
Fields present in the sample are required by default; adjust optionality to match your actual API contract.
How are nested objects typed?
Each nested object becomes its own interface, named and referenced from the parent type.
Is my sample JSON uploaded?
No. Interface generation happens entirely in your browser.
Last reviewed: October 2026.