Free Protect PDF
Add broadly compatible RC4 128-bit password protection to a PDF, directly in your browser.
Add a PDF to protect
Choose a PDF file.
Maximum 100 MBCompatibility protection: uses older RC4 128-bit PDF encryption, not modern AES-256. Do not use for highly sensitive or regulated documents.
Processed in your browser. Your PDF and password never leave your device.
How to add a password to a PDF
- Add a PDF file.
- Enter and confirm a password.
- Select Protect PDF.
- Download the encrypted PDF.
How this works
Your browser applies the older, broadly compatible PDF RC4 128-bit security handler directly to document strings and streams. It is genuine password-based encryption rather than a visual lock overlay, and no file or password is uploaded.
Security limitation
RC4 128-bit PDF protection is retained for compatibility with many readers, but it is an older scheme and is weaker than modern AES-256 PDF encryption. Do not rely on this tool for highly sensitive, regulated, or high-risk documents; use a current security product that explicitly supports AES-256 instead.
Common use cases
- Add compatibility-focused password protection before sharing a PDF
- Require a password to open a PDF in common readers
- Protect a routine document when modern AES encryption is not required
Frequently asked questions
Is this PDF protection tool free?
Yes. It is completely free, with no signup and no limits.
Is my PDF or password uploaded anywhere?
No. Encryption happens entirely in your browser. Nothing is sent to Inqita or stored.
Is this real encryption, or just a lock icon?
It applies genuine RC4 128-bit PDF encryption, not a visual overlay. RC4 is an older compatibility-focused scheme and is not equivalent to modern AES-256 protection.
What happens if I forget the password?
The PDF cannot be opened without it — there is no recovery. Keep your password somewhere safe.