Protect PDF
Mark a PDF as confidential in your browser — flatten form fields and stamp a bold watermark. Honest about why true password encryption needs a desktop app.
About the Protect PDF
This tool takes an honest approach to "protecting" a PDF. Real password encryption rewrites a document's internal data with a secret key, and that cannot be done safely or reliably with browser-only libraries — so we don't fake it. A password bolted on client-side would give a dangerous false sense of security.
What it does do, entirely on your device, is genuinely useful: it flattens interactive form fields so their values can no longer be edited, and stamps a bold diagonal watermark (CONFIDENTIAL by default, or your own text) across every page. That clearly signals a document's status and deters casual copying or reuse.
For true encryption with an open or permissions password, use a desktop tool such as Adobe Acrobat, LibreOffice (File → Export as PDF → Security) or the free qpdf command-line utility. Everything here runs in your browser with no upload, so even the marking step keeps your file private.
How to Use the Protect PDF
- 1Read the note on what browser-based protection can and can't do.
- 2Upload the PDF you want to mark.
- 3Keep the CONFIDENTIAL watermark text or type your own.
- 4Click Flatten & Watermark and download the marked PDF.
Frequently Asked Questions
Can this add a password to open my PDF?
No, and we're upfront about it: genuine password encryption isn't something a browser-only tool can do securely, so we don't pretend to. For a real open or permissions password, use Adobe Acrobat, LibreOffice's PDF export security options, or the qpdf command-line tool on your computer.
What does the tool actually do to protect my file?
It flattens any fillable form fields so their contents become permanent, and stamps a bold diagonal watermark across every page to mark the document as confidential. This is a strong visual deterrent and prevents easy form edits, though it is not cryptographic security.
Can the watermark be removed?
The watermark is drawn into each page's content rather than added as a removable annotation, so it survives printing and re-saving. A determined user with a professional PDF editor could still remove it, so treat it as a deterrent and status label rather than tamper-proof protection.
Is my document uploaded?
No. The file is flattened and watermarked entirely in your browser and never sent to a server, which is exactly the privacy you want for confidential documents.