Protect PDF Online
Add permissions, passwords and restrictions to PDF documents.
Runs entirely in your browser
Upload PDF to Password Protect
Choose fileRate Protect PDF4.8(195 votes)Rate Protect PDF
How to use Protect PDF
- 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.
Privacy & security
Password encryption is applied to your PDF entirely within your browser using the pdf-lib library. Your document is never uploaded or transmitted.
Your document and password are processed locally. No data is transmitted to any server.
Frequently asked questions
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.