Safe and local: what happens to your file when you process it online

What happens when you upload to a server

With server-side processing, your browser sends the file over the internet to a remote computer. It's processed there — for example unlocked, password-protected, or compressed — and the result is sent back for download. The original file necessarily leaves your device, even if it's deleted afterward. This is technically required for tools that depend on software that only exists as server software, not as browser code — on ConverterFleet, for example, PDF unlocking, PDF password protection, and PDF optimization.

What local browser processing technically means

With local processing, your browser reads the file directly from your device and processes it using its own built-in capabilities — without opening a connection to any server for that operation. The finished result is then offered for download, without the file ever having left your device. On ConverterFleet, for example, merging multiple PDF files runs entirely locally in your browser.

How to verify the difference yourself

You don't have to take anyone's word that a process runs locally — it's technically verifiable. Open your browser's developer tools (usually F12) and switch to the Network tab before processing a file. If the operation runs locally, no request transferring your file will appear there. If it runs server-side, you'll see an upload request with the file size. ConverterFleet also visibly marks which processing mode each tool page uses — so checking is never required, just always possible.