How to password-protect a PDF
To password-protect a PDF, open the Protect PDF tool, add your file, set a password, and download the encrypted copy — PDFER encrypts it with AES-256 in your browser, so the file and password are never uploaded. To take a password off a file you can already open, use Remove Password.
Adding a password
In Protect PDF, choose a strong password and confirm it. The tool encrypts the document with AES-256; anyone who opens it afterward must enter that password.
There is no recovery — if you forget the password, the file cannot be opened, so store it somewhere safe.
Removing a password
If you know a PDF's password and want to share an unlocked copy, use Remove Password: enter the password and download a decrypted version.
This is different from Unlock, which only strips usage restrictions (like no-printing) from a file you can already open — it can't open a file that requires a password.
How strong is it?
AES-256 is strong; the real weak point is the password itself. A short or common password can be brute-forced offline, so use a long, unique one.
Tools mentioned in this guide
Frequently asked
- Is password protection done without uploading my file?
- Yes. PDFER encrypts the PDF with qpdf compiled to WebAssembly, entirely in your browser — the document and the password never leave your device.
- Can PDFER open a password-protected PDF I've lost the password to?
- No. Remove Password decrypts using a password you provide; it does not crack or bypass unknown passwords.