Type Generator
Convert JSON to TypeScript Interfaces
Generate typed TypeScript interfaces from your JSON in one click — accurate, readable, and fully client-side.
100% In-Browser & PrivateNo uploadsFree forever
Stop hand-writing type definitions. MyJSONPal converts any JSON document into clean, strongly-typed TypeScript interfaces: objects become interfaces, arrays become typed lists, and nested structures are extracted into named, reusable interface types.
The generator is smart about naming — keys are converted to PascalCase interface names so you get meaningful, human-readable types like Chapter or AuthorMetadata instead of anonymous ObjectN literals. Root-level primitives and arrays are emitted as a type alias, and consistent types keep your API contracts aligned with your runtime data.
Because the generation runs entirely in your browser, you can convert internal API responses and private schemas without a single upload. The output is ready to paste into your tsconfig-based project.
How to generate TypeScript types
- 1Paste a JSON sample of your API response or data shape.
- 2Select TypeScript from the format dropdown.
- 3Copy the generated interfaces to your clipboard.
- 4Paste them into a .ts file in your project.
- 5Iterate: paste a new sample whenever the API shape changes.
Why MyJSONPal is different
Privacy-first, by design
All parsing, validation and conversion runs in your browser. Your data is never sent, logged, cached or sold — close the tab and it is gone.
Fast, even on huge files
Heavy processing is offloaded to a Web Worker, so multi-megabyte documents are handled without freezing the interface.
No accounts, no limits
There is nothing to sign up for and no usage quota. Paste, format, convert and download as often as you like.
Frequently asked questions
How are arrays typed?
Arrays of objects become a named interface with a [] suffix (for example Chapter[]). Arrays of primitives become string[], number[], and so on.
What about null values?
Explicit null fields are typed as null. If a field can vary, the generated type reflects what is present in your sample; you can refine it with optional markers or unions afterward.
Are the generated interfaces valid TypeScript?
Yes. The output uses standard interface and type-alias syntax that compiles under any modern TypeScript configuration.
Does it work for large documents?
Yes. Generation runs in a Web Worker, so even big payloads produce types quickly without blocking the page.