JSON → TypeScript Interface converter
Generate clean TypeScript interfaces from JSON locally in your browser, with nested object and array support.
Paste your source, then convert it locally.
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Conversion directions
Direction 01
JSON to TypeScript Interface
Generate clean TypeScript interfaces from JSON.
About this converter
Generating TypeScript interfaces from JSON
Paste a JSON object and the converter produces clean, idiomatic TypeScript interfaces, one per nested object, with descriptive names derived from the keys. Arrays become T[], optional fields are marked, and the output is ready to paste directly into a .ts file.
The generated types let the compiler catch spelling mistakes and schema drift at build time instead of at runtime.
Naming and nesting
Each nested object is promoted to its own interface and named after its parent key in PascalCase, which keeps deeply nested payloads readable. Union types and optional members are inferred when a field is null or missing, so the types reflect real API responses.
Using the generated types
Add the interfaces to your project and annotate fetch or API client calls with them. Pair the types with a runtime validator such as zod when you consume untrusted data, so both compile-time and runtime safety are covered.
Frequently asked questions
Can this converter infer nested TypeScript interfaces?
Yes. Nested objects generate separate interfaces and arrays infer their element types.
Is the generated TypeScript editable?
Yes. Copy or download the output and adapt the generated interfaces in your project.
Does it mark optional fields?
Yes. Fields that are null or missing in the JSON are marked optional, so the types reflect real API responses that may omit keys.
How are nested objects named?
Each nested object is promoted to its own interface, named after its parent key in PascalCase to keep deeply nested payloads readable.
Can I paste the output into a .ts file?
Yes. The output is idiomatic TypeScript with imports and is ready to paste directly into your project.
Does it work with arrays?
Yes. JSON arrays become T[] syntax with the correct element type inferred from the data.