JSON to TypeScript Interfaces

Paste JSON or upload a .json file and generate clean TypeScript interfaces instantly. 100% client-side. No uploads.

JSON Input

TypeScript Output

Input: 0 chars Interfaces: 0 Fields: 0 Output: 0 chars

🔒 PRIVACY NOTE: Your files are processed entirely within your web browser. We do not upload, store, or share your data with any servers. 100% secure and private.

How it works

Convert any JSON object, array, or API response into clean, typed TypeScript interfaces in three simple steps.

Paste or Upload JSON

Paste a JSON object, an array of objects, an API response, or upload a local .json file directly from your device. The converter handles nested structures automatically.

Customize Settings

Choose between interface or type, set the root name, pick indentation, and decide how optional, null, union, and readonly fields should be handled.

Copy or Download

Review the generated TypeScript definitions, copy them to your clipboard, or download a ready-to-use .ts file straight from your browser.

Frequently Asked Questions

Is this tool completely free?

Yes! File Gulp provides completely free file conversion tools with no hidden fees, no watermarks, and no registration required.

Are my files safe?

Absolutely. Unlike other converters, File Gulp uses modern WebAssembly technology to convert files directly on your device. Your files never leave your computer, ensuring maximum privacy.

Does it work on mobile devices?

Yes, our tool is fully responsive and works perfectly on smartphones and tablets, directly from your mobile browser.

Will the quality be affected?

No, we use high-quality algorithms to ensure your output files maintain the best possible quality during conversion.

Is there a file size limit?

Very large files may be limited by your device memory/browser performance. For normal image sizes, conversion is fast and seamless.

JSON

Turn API responses into reliable types

When you receive JSON from an API, CMS, database export, webhook, or configuration file, TypeScript interfaces help describe the shape of that data. This makes autocompletion better, reduces mistakes, and helps developers understand nested objects faster.

TypeScript

Interfaces that match real data

This converter inspects actual JSON values and infers practical TypeScript types such as string, number, boolean, arrays, nested objects, nullable values, and union types when fields contain mixed data.

Why this JSON to TypeScript converter is different

Many simple converters only work well for flat JSON. File Gulp focuses on real-world API data with nested objects, arrays, missing fields, and privacy-first local processing.

100% client-side: Your JSON is parsed locally in your browser and is never uploaded to a server.
Nested interface generation: Objects inside objects and arrays are converted into readable named interfaces.
Optional field detection: Arrays with different object shapes can mark missing properties as optional.
Union type support: Mixed values become useful unions like string | number instead of vague any.
Developer-friendly output: Choose interface or type, export keyword, readonly fields, semicolons, and indentation.

Use Cases

Common reasons to generate TypeScript from JSON

Use this tool for REST API responses, GraphQL samples, webhook payloads, Firebase or Supabase exports, Stripe-style event objects, settings files, translations, product feeds, and mock data used in frontend projects.

Privacy

Safer for private payloads

API responses often contain customer IDs, emails, internal URLs, tokens, or business data. A browser-only JSON to TypeScript converter lets you generate interfaces without sending that sensitive data to another website.