Why this exists
Most file converters online work the same way. You upload your file, a server somewhere does the work, and you download the result. It's fine, and it usually works. But it also means a copy of your file — which might be a passport scan, or a tax return, or photos off your phone — ends up on a machine you don't control, run by a company you hadn't heard of ten minutes earlier. You're trusting a privacy policy you didn't read, and there's no way to check whether it's being followed.
What makes it worse is that plenty of these conversions don't need a server at all. Your computer can already do them. Preview on a Mac will export a HEIC as a JPEG from the File menu. But that's a piece of technical trivia, and there's no particular reason anyone would have picked it up. So people search for a converter, land on a site that asks for an upload, and hand over a file that never needed to leave the folder it was sitting in.
What this does instead
ChangeFile uses the same underlying libraries those servers use — libvips for images, libarchive for archives — compiled to WebAssembly so they run inside your browser tab. Your file goes from your disk into the page and back out as a download. There's no upload to opt out of, because there's no upload. No account either, and nothing left on a server afterward.
The tradeoff is that this site does less than the big ones. If an operation can't run on your device, it isn't supported here.
Verify it yourself
Two ways to check:
- Open your browser's developer tools, go to the Network tab, and convert something. You'll see the page load and the WebAssembly engine download. You won't see your file go anywhere.
- Or skip that entirely: load the site, turn off your Wi-Fi, and convert a file. It still works, which wouldn't be possible if the work were happening somewhere else.