Protect PDF (Add Password)
Protect PDF adds a password to a PDF using strong AES-256 encryption, so it can only be opened by someone who knows the password. It runs entirely in your browser using qpdf compiled to WebAssembly — your document and password never leave your device.
Last updated: July 2026
To password-protect a PDF, choose the file, set a password, and download the encrypted copy. Encryption uses AES-256 and runs entirely in your browser via qpdf, so your PDF and password are never uploaded.
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How to use Protect PDF (Add Password)
- Choose a PDF file.
- Enter and confirm a password.
- Click Protect and download the encrypted PDF.
Frequently asked questions
How strong is the encryption?
It uses AES-256, the modern standard supported by current PDF readers.
Can the password be recovered if I forget it?
No. There's no backdoor — if you lose the password, the PDF can't be opened. Store it safely.
Is my PDF uploaded?
No. Encryption happens in your browser; the file and password never leave your device. The only download is the one-time engine (~1.3 MB).
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