Convert JSON to TypeScript

Free, no login, and your file never leaves your device.

Open the JSON → TypeScript tool

JSON to TypeScript, converted on your own machine

Converting JSON to TypeScript normally means handing your file to a website that uploads it, processes it on a machine you cannot inspect, and asks you to trust a retention paragraph. FileForge removes that step: the JSON → TypeScript tool runs inside this browser tab, so a JSON file becomes TypeScript without ever crossing the network.

Drop in a sample API response and get clean, nested TypeScript interfaces back, with arrays, unions, and optional fields inferred. Everything happens locally in your browser: nothing is uploaded, stored, or logged.

Because the conversion happens on your hardware, throughput depends on your CPU rather than a shared free tier — there are no file-size caps, no watermarks, no daily quotas, and no paid tier that unlocks the real feature set. It also means the page keeps working offline in the browser once loaded, which is handy for confidential material on a locked-down laptop or a phone in aeroplane mode. One honest caveat: types are inferred from one sample, so fields that are null or missing in that sample are typed loosely.

Read how the in-browser processing works.

How to convert JSON to TypeScript

  1. 1

    Open JSON → TypeScript

    Open the JSON → TypeScript page on FileForge. No sign-up, install, or extension is needed — the tool loads as a normal web page.

  2. 2

    Add your file

    Paste or drop your file into the panel, or click to browse. The file is read locally in your browser and is never uploaded.

  3. 3

    Choose your settings

    Adjust the options in the settings panel — generate interfaces from a json sample — until the result matches what you need.

  4. 4

    Run and download

    Press the action button, wait for processing to finish on your own CPU, then download the result straight from the page.

JSON to TypeScript — frequently asked questions

Do I need to create an account to use JSON → TypeScript?
No. FileForge requires no sign-up or login — just open the tool and use it.
Is JSON → TypeScript really free?
Yes, completely free with no hidden limits or premium paywall.
Does JSON → TypeScript upload my file to a server?
No. Everything runs locally in your browser. Your file is never uploaded, stored, or transmitted anywhere.
Is there a file size limit?
There is no artificial limit. The practical ceiling is your device's available memory, so very large files work best on a desktop browser with plenty of free RAM.
Does JSON → TypeScript work offline in the browser?
Once the page (and, for audio and video, the FFmpeg engine) has loaded, the tool keeps working without a network connection because all of the processing code already lives in your browser.
Is JSON → TypeScript private enough for confidential documents?
Yes. Because the file is processed on your own CPU, contracts, medical scans, ID photos and payroll data never travel over the network — you can verify that with your browser's network tab open.
Which browsers are supported?
Any modern browser with WebAssembly support — Chrome, Edge, Firefox, Safari, and their mobile versions. No plugins or extensions are required.
What are the limitations of JSON → TypeScript?
Types are inferred from one sample, so fields that are null or missing in that sample are typed loosely.