How it works
How UnplugPDF works without uploading your files
UnplugPDF runs each PDF tool inside your browser tab. Here is what happens to your file, what the site sends, and how to check it yourself.
The short answer
UnplugPDF sends the tool to your file instead of sending your file to a server. Your browser downloads each tool once, runs it inside the tab, and saves the result back to your device. No file ever crosses the network.
What crosses the network
Most online PDF tools
Your file crosses the network twice.
UnplugPDF
Only the tool's code crosses, once. Your file stays put.
What happens when you open a tool?
The browser downloads the page and, on first use, the tool's engine (several MB of WebAssembly and fonts). It keeps both, so the tool then works offline.
What happens to your file?
It is read from your device into the tab's memory and processed in a background worker inside the tab. It never passes through the service worker or the network, and the working copy is cleared when you close the tab. Files shared to the installed app are held on your device for seconds, until the page picks them up.
What does the site send?
The complete list: ordinary page requests to Cloudflare, which hosts the site; anonymous counts (tool opened; job started, finished or failed; free limit reached; Pro link followed; app installed; coarse size ranges), sent after a job ends; the Pro licence check (receipt ID or licence token plus a random device ID); and network-error reports to Cloudflare. Nothing else, and never file content or names.
How can I check it myself?
Wi-Fi test: run a tool once, switch off Wi-Fi, run it again.
Network tab: open your browser's developer tools, run a tool, and look at every request. None carries your file. Apart from the tool's engine on first use, the only requests are small counts sent to this site.
Security policy: view the page source and find
connect-src 'self'. It tells your browser to block data going to any other site.
What are the limits?
Each tool needs internet the first time you use it. Clearing site data or using a private window removes the offline copy. Your device's own security still matters: malware, or a browser extension allowed to read pages, can see what any page shows.
Which open-source software does it use?
PDFium, qpdf, pdf-lib, HarfBuzz, Tesseract and other open-source projects, all running inside your browser. Their licences are listed in full:
Third-party licences