Password Protect PDF — Free.
No Upload. Encrypted in Browser.

Frequently asked questions

• Is my password sent to any server?+
  No. The password and PDF are processed entirely in your browser. Neither the file nor the password is transmitted to any server at any point. You can verify this by watching your browser's network tab while the encryption runs.
• What encryption does this use?+
  pdf-lib applies standard PDF encryption. The resulting protected file requires the password to be opened in any PDF viewer — Adobe Acrobat, macOS Preview, Chrome, Firefox, etc. This is the same standard used by Smallpdf, Adobe, and other services, except ours runs locally.
• What if I forget the password?+
  We cannot recover it — we never had it. Store your password securely (use a password manager) before encrypting. Always keep an unencrypted copy of the original file as a backup.
• Can I remove the password later?+
  You would need a tool that can open password-protected PDFs with the correct password and re-save without encryption. Adobe Acrobat and macOS Preview both support this. We don't currently offer an unlock PDF tool.
• Does this work on all PDF viewers?+
  Yes. Standard PDF password encryption is supported by every major PDF reader — Adobe Acrobat, macOS Preview, Chrome, Firefox, Edge, and PDF apps on iOS and Android.
• Does this work on mobile?+
  Yes. The tool is fully responsive. Pick a PDF, enter a password, and download the protected file — works on phones and tablets in any mobile browser.