Protect PDF Online
Use this free online Protect PDF tool to add permissions, passwords and restrictions to PDF documents client-side.
Upload PDF to Password Protect
PDF security processing is kept entirely local
How it works & FAQ
Why this is secure?
Password encryption is applied to your PDF entirely within your browser using the pdf-lib library. Your document is never uploaded or transmitted.
Step-by-Step Guide
- 1Upload the PDF you want to protect.
- 2Enter a strong password in the password field and confirm it.
- 3Click 'Protect & Download' — the encrypted PDF saves to your device.
Frequently Asked Questions (FAQ)
What encryption standard is used?
PDFs are encrypted using AES-256 via the pdf-lib library — consistent with major PDF readers including Adobe Acrobat.
Can I protect a PDF that's already protected?
No — you'd need to unlock it first, then re-protect it with a new password.
Will the protection work in Adobe Acrobat?
Yes. The password protection is compatible with Adobe Acrobat, Preview, and all major PDF readers.
Your document and password are processed locally. No data is transmitted to any server.