Password Protect PDF Online — Lock Your PDF Free
Lock your PDF so it can only be opened with the correct password. Encryption runs entirely in your browser — your password is never sent to any server.
How to protect pdf online — 3 easy steps
- Step 1: Upload the PDF to protect.
- Step 2: Enter a strong password.
- Step 3: Click Protect and download the password-locked PDF.
Why use FileMasterPDF to protect and unlock PDF documents
- Password never transmitted: encryption runs entirely in your browser.
- Immediate results: lock or unlock a PDF in under a second.
- No account needed: no registration or email address required.
- All PDF versions supported: works with PDFs from any application.
- Completely free: no subscription, no trial period, no limits.
Frequently asked questions — Protect PDF
Can it be opened without the password?
No — the PDF is encrypted and unreadable without the correct password.
Where is my password stored?
Nowhere — it's used to encrypt the file in your browser then discarded.
What encryption is used?
Strong browser-based encryption that prevents casual access.
Can I protect an already-protected PDF?
Unlock it first with Unlock PDF, then add a new password.