How our tools work
PDF sites that work on a server send your file to their server, change it there, and send it back. Our tools do the work inside your own web browser instead. Your file is read and changed on your phone or computer, and it is never uploaded.
What happens when I add a file?
Your browser reads the file from your device into its own memory. Open-source PDF code, which downloaded with the page like any other script, then does the job: joining pages, turning pages into images, adding a password. The result is saved straight from memory to your downloads folder.
The heavy PDF code loads only after you pick a file, so pages open fast. It runs in a background worker, so the page stays responsive while a large file is processed.
How can I check that nothing is uploaded?
You can prove it in under a minute. Open any tool, let the page finish loading, then turn off Wi-Fi and mobile data. Add a file and run the tool. It still works, because nothing needs to travel over the internet. On a laptop you can also watch the browser's network panel while you use a tool.
- Open a tool page and wait until it has finished loading.
- Turn off Wi-Fi (and mobile data on a phone), or switch on airplane mode.
- Add your file and press the main button. The tool finishes and offers the download.
- Optional, on a laptop: press F12, open the Network tab, and use the tool. No request carries your file.
Our guide Is It Safe to Upload a PDF Online? shows the result of this test on Compress PDF and explains how to check any other site.
Are there any limits?
The limit is your device memory, because your device does the work. Phones have less memory than laptops, so very large files, or many large files at once, can fail on a phone. Each tool checks the total size first and tells you when it is too much, instead of letting the browser tab crash.
What does load from the internet?
The pages themselves, the PDF code they use, and, once switched on, analytics and ads. Those services can see that a page was visited, like on any website. They never receive your files or their contents. The privacy policy lists every outside service by name.
Read the privacy policy and the list of open-source libraries the tools are built on.
When I continue in another tool, where does my file go?
When you press a tool name under Or continue in, the result is kept in your browser's own storage for a moment so the next tool can open it without a new download. It stays on your device, is removed as soon as the next tool reads it, and expires after ten minutes either way.