JSON to TypeScript Converter
ConvertTurn a JSON sample into clean, ready-to-use TypeScript interfaces in one click.
Generate TypeScript interfaces from JSON
Hand-writing TypeScript types for an API response is tedious and error-prone. Paste a representative JSON sample here and get a complete set of TypeScript interfaces back instantly — typed, nested, and ready to paste into your project.
Every value is mapped to its TypeScript type: strings, numbers, booleans, and null are inferred directly, and each nested object becomes its own named interface so the result is clean and reusable rather than one giant inline type.
Smart handling of arrays and optional fields
Real data is messy, and the generator handles it. An array of objects is merged into a single interface that accounts for every element, so you get one accurate Item type instead of dozens. Any key that appears in some objects but not others is marked optional with a ?, and arrays of mixed scalars become a union like (string | number)[]. Rename the root interface to fit your domain and the types are production-ready. The guide to generating TypeScript types from JSON goes deeper on how types are inferred and how to handle tricky shapes.
Generate TypeScript types from an API response
The fastest way to type an external API is to let a real response do the work. Paste a JSON sample and generate TypeScript interfaces online — nested objects become their own named interfaces, optional fields are detected across array items, and mixed arrays become unions. Copy the result into your project and you have accurate types without transcribing a single field by hand.
Everything in the JSON to TypeScript Converter
Convert JSON to TypeScript interfaces instantly. Infers types, generates nested interfaces, merges array items, and marks optional fields. Paste a JSON sample and get typed interfaces. Free, private, in-browser.
Named interfaces
Every nested object becomes its own named, reusable interface.
Type inference
Strings, numbers, booleans, null, and arrays are typed automatically.
Optional fields
Keys missing from some array items are marked optional with ?.
Arrays merged
An array of objects collapses into one interface covering every item.
Frequently asked questions
The converter reads your JSON sample and maps each value to a TypeScript type: strings to string, numbers to number, booleans to boolean, and objects to named interfaces. Nested objects get their own interfaces named after their key, so the output is clean and reusable.
An array of objects is merged into a single interface that covers every element — and any key that's missing from some elements is marked optional with a ?. Arrays of mixed scalar types become a union, such as (string | number)[].
Yes. The result is standard, exported TypeScript interfaces (and type aliases for non-object roots) that you can paste straight into a .ts file. Rename the root interface to match your domain and you're done.
No. Every operation runs entirely in your browser using client-side JavaScript. Your JSON is never uploaded, logged, or stored on any server — it never leaves your device.
Yes, completely free with no sign-up required. There are no usage limits, no watermarks, and no premium gate on any feature.
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