About PDF password protection
Encrypting a PDF means the file itself is scrambled with AES-256 — the same encryption standard used for banking and government documents — and only your password can unscramble it. This tool runs the respected open-source qpdf engine, compiled to run inside your browser, so the file and the password stay on your device from start to finish. That matters: uploading a document to a website in order to "secure" it is a contradiction most free tools quietly ignore.
How to password protect a PDF
- Add your PDF file.
- Enter a password twice. Longer is stronger — a short password can be guessed by software regardless of how good the encryption is. Our password generator makes strong ones.
- Press Encrypt PDF. The first run loads the encryption engine (about a megabyte); after that it's instant.
- Download the protected copy and store your password safely.
Important notes
- There is no password recovery. Nobody — including us — can open the file if the password is lost, because we never see either.
- The original unprotected file remains on your disk; delete it if the content is sensitive.
- To remove protection later, use Unlock PDF with the current password.
Frequently asked questions
How strong is the encryption?
AES-256 — the current industry standard, used by banks and governments. With a good password, brute-forcing it is not practical with today's technology. Password strength is the weak point, so use a long one.
What happens if I forget the password?
The file cannot be opened by anyone — there is no backdoor and no recovery, precisely because the encryption is real and we never see your password. Store it in a password manager.
Is my PDF or password sent to a server?
No. The encryption engine (open-source qpdf) runs inside your browser; both the file and password stay on your device from start to finish.