Guides
How to tell what a tool does with your file
Most free converters send your file to a server, process it there, and send it back. That is not a scandal, it is an architecture — and you can check it yourself in about two minutes. These guides show the check, then show what a tool that never uploads looks like from the inside.
- Test any online tool: did my file leave this computer?A two-minute check with the browser you already have. Works on any site, including this one.
- Merge PDFs without uploading themWhat a server actually does with the file, and what changes when the work happens on your machine instead.
- Compress photos without uploading themWhy photos leak more than documents — location and camera data travel inside the file — and how to strip them.
- Convert iPhone photos without uploading themHEIC exists because phones save space. You do not need someone else's server to read it.
Everything on this site runs in the browser, so there is no upload to check for. If that claim ever stops being true, the format test above is how you would catch it.