Protect PDF

Add password to PDF.

Honest limitation: real PDF password encryption requires server-side processing, which this site does not have. The pdf-lib library used here cannot apply real password protection in the browser. Instead, this tool lets you stamp a visible "CONFIDENTIAL" (or custom) watermark across every page as a practical, real, working alternative to discourage casual sharing. It is not encryption and can be removed by anyone with basic PDF editing tools.

Click or drag a PDF here to upload

Supports single PDF files

Frequently Asked Questions

Why can't this tool set a real password?+

Genuine PDF encryption needs cryptographic libraries and processing that browsers and the client-side pdf-lib library don't provide, and this site has no server-side PDF processing. Rather than fake a password field that doesn't actually protect anything, we're upfront that this tool offers a visible deterrent watermark instead.

Does the watermark actually protect my PDF?+

It's a visual deterrent, not encryption. Anyone with PDF editing software could remove it. If you need real password protection, use desktop software like Adobe Acrobat or a trusted server-side tool.