Free PDF Password Protector
Add password protection to any PDF with RC4-40 encryption — processed entirely in your browser. Your file is never uploaded to any server. Free, instant, no signup.
Drop a PDF here or click to upload
PDF files only · Max 20 MB
How it works
- Your PDF is sent over HTTPS, encrypted in memory, and returned — never stored.
- Uses RC4-40 encryption (PDF Standard Security Handler, Revision 2), compatible with all PDF readers.
- The open password is required to view the file. The owner password restricts editing, printing, and copying.
Why Use This PDF Locker?
Built for privacy and compatibility — works with every PDF viewer.
RC4-40 Encryption
Industry-standard PDF encryption compatible with all major PDF viewers.
Never Uploaded
PDF is encrypted in your browser with pdf-lib — it never reaches any server.
Owner + User Passwords
Set both a user (open) password and an owner (permissions) password.
Instant Download
Encrypted PDF is ready to download immediately after processing.
When Should You Password-Protect a PDF?
Password-protecting a PDF is a simple but effective layer of access control. Common use cases include:
- Confidential reports — financial statements, business plans, or strategy documents shared with stakeholders.
- Legal contracts — NDAs, service agreements, and employment contracts distributed to multiple parties.
- Personal documents — passports, ID documents, medical records, or tax returns sent via email.
- Premium content — ebooks, courses, or reports sold online that should only be readable by the purchaser.
- Exam papers — tests or assessments that must remain sealed until a specific time.
Since this tool processes everything in your browser, it is especially safe for documents that must never be uploaded to unknown servers — such as government-issued IDs, banking documents, or client contracts.
Frequently Asked Questions
Everything about PDF password protection.
What encryption does this PDF locker use?
RC4-40-bit encryption — widely supported by all major PDF viewers including Adobe Acrobat, macOS Preview, and mobile apps. Compatible with all PDF readers.
Is my PDF uploaded to a server?
No. Encryption happens entirely in your browser using pdf-lib. Your PDF never leaves your device — safe for confidential documents.
Can I unlock a PDF with this tool?
No — this tool only adds password protection. To unlock a PDF, use Adobe Acrobat or macOS Preview with the original password.
What happens if I forget the password?
There is no recovery option. PDF encryption is irreversible without the password. Always keep a backup of the unprotected original file.
Will password-protected PDFs work on all devices?
Yes. RC4-40 encrypted PDFs are compatible with all major PDF apps — Adobe Acrobat, macOS Preview, iOS, Android, Foxit, and browser PDF viewers.