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. Select several PDFs to apply the same password to the whole set in one pass and download them together as a .zip. 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.
How to use Protect PDF (Add Password)
- Choose one or more PDF files.
- Enter and confirm a password.
- Click Protect and download the encrypted PDF — or “Download all” as a .zip for a batch.
Frequently asked questions
How strong is the encryption?
It uses AES-256, the modern standard supported by current PDF readers.
Can I password-protect several PDFs at once?
Yes. Select multiple PDFs and the same password is applied to each one, encrypted one file at a time, then offered individually or as a single .zip.
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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