UnProton Labs builds small, dependable software for the work most tools overcomplicate — including PDFStamper, the private way to mark up a document.
We start from a simple idea: most software does too much. So we build the opposite — tools narrow enough to master in a minute, light enough to forget they're running, and honest enough to keep your data on your machine when it belongs there.
PDFStamper came out of a small frustration that turns out to be everyone's frustration. Adding an "APPROVED" mark, a signature, or a Bates number to a PDF usually meant uploading a sensitive document to a website you'd never heard of — or wrestling with a bloated desktop suite. Neither felt right for a contract, an invoice, or an ID.
So we made a tool that does that one job properly and keeps the file where it started: in your browser, on your device, never on a server. Three tools today, more on the way. Same name, same standards, same promise.
Depth over breadth, always. No feature creep, no menus you'll never open — just the job, done properly.
No dark patterns, no lock-in, no nagging. Free to install, free to leave, with nothing held hostage.
If a tool can run on-device, it does. Your files and figures stay in the browser, not in someone's cloud.
UnProton is built to scale. Each new tool plugs into the same brand, the same standards, and the same promise.
Highlight anything dense on the web and get a clear, plain-language explanation in place — at the exact depth you need.
explainly.unproton.com ↗A clean, offline PDF invoice generator for freelancers and small businesses. No signup — your numbers never leave the browser.
Coming soonStamp, sign and watermark any PDF without uploading a single file. Everything happens on your device.
You're here →No account, no setup, no commitment. The whole point is that it just works.