How to check that a "privacy-first" tool is actually private

Every file tool on the internet claims to respect your privacy somewhere in its footer. Most of them upload your file to a server anyway — the claim and the architecture are two different things, and only one of them is checkable.

The fastest way to verify a tool actually processes files locally: open your browser's developer tools (F12, or right-click → Inspect), go to the Network tab, then use the tool as normal — pick a file, run the action, download the result. If the tool is genuinely client-side, you will not see your file's bytes appear in any outgoing request. You'll see the page's own JavaScript and CSS load once, and nothing else, no matter how large the file you process.

A server-based tool looks different: right after you select a file, you'll see a POST request with a body roughly the size of your file, heading to some API endpoint. That's the moment your file left your device, regardless of what the privacy policy says happens to it afterward.

A second check, when it's available: open-source code. If a tool links to a public repository, you (or anyone) can read the exact code that runs in your browser and confirm there's no hidden upload path. We link ours in the footer of every tool page for this reason — take us up on it rather than taking our word for it.

One caveat worth knowing: a tool can be client-side for the main operation but still upload something incidental — an analytics ping, a font file, an ad request. That's normal and mostly harmless, but it's different from your actual document data leaving the browser. The network tab will show you the difference: look at what's being sent, not just how many requests there are.