If a PDF contains sensitive information — financial records, contracts, personal documents — adding a password means only people with that password can open it. Here's how to do it safely.
How PDF passwords work
A password-protected PDF is encrypted: its contents are scrambled and can only be unlocked with the correct password. Anyone who gets the file without the password can't read it.
Try it nowProtect PDF — free, in your browser, nothing uploaded.
Open Protect PDF →Do it locally for sensitive files
For genuinely private documents, use a tool that encrypts in your browser without uploading. That way the unprotected file never sits on someone else's server.
Don't lose the password
There's no 'forgot password' for an encrypted PDF. If you lose it, the file generally can't be opened. Store it somewhere safe.