Free PDF Tool · Security

Password Protect PDF

Password Protect PDF is a browser-based PDF tool on PDFToolsBase. Password Protect PDF: free password protect pdf in your browser. No server upload, no signup, no watermark. Works on Windows, Mac, Linux, iOS, Android. To use it, upload or drop your PDF and view the result directly in your browser — no signup and nothing to install.

Run password protect pdf in your browser. Free, private, no signup — your selected files are processed in your browser and are not uploaded to our server.

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Drop your file here

or click to browse from your device

Accepts: .PDF
Before encrypting: This tool applies AES-256 password protection (PDF revision 6) locally in your browser. It preserves original page content without rasterizing or flattening text and forms.
  • Keep the password safely; this site cannot recover it.
  • Choose a different open password to limit recipients to the selected permissions. The owner password provides full access.
  • Printing, copying and editing restrictions depend on the PDF reader and cannot prevent screenshots.
  • Encryption is not a digital signature; rewriting an already signed PDF can invalidate its signatures.
  • Open the download in your intended reader and confirm its content before sharing.

About this Password Protect PDF

Encrypt your PDF with a password using our password protect pdf tool. Type a password (at least 4 characters) and we apply AES-256 protection to the original PDF content without converting pages to images. The PDF readers should require the password to open the output.

The encryption uses AES-256 with the PDF revision 6 security handler, provided by the locally bundled @cantoo/pdf-lib library. PDF readers should require the password to open the output. Use a strong password; weak passwords can be guessed and there is no recovery if you forget it. Important: there is no password recovery — keep yours safe.

Your privacy is the default. Your selected files are processed in your browser and are not uploaded to our server; all document encryption happens client-side using the locally bundled @cantoo/pdf-lib library. Closing the tab clears the working session from this page; downloaded files remain on your device.

This tool is free to use with no signup required. Large files may be limited by your browser’s memory and device performance. Part of PDF Tools Base, a privacy-first collection of 161 PDF utilities. Bookmark the page for next time, and explore related tools in the footer below.

How to use the Password Protect PDF tool

  1. Drop your PDF into the upload area.
  2. Enter a password to require for opening; copying stays disabled while printing is allowed.
  3. Click Process to apply password encryption.
  4. Download the password-protected PDF.

Why use PDF Tools Base?

100% Browser-Based

Password Protect PDF processes selected files in your browser. Your selected files are processed in your browser and are not uploaded to our server.

No Server Upload, No Signup

Your selected files are processed locally in your browser. No account, no server upload, no email needed.

No Watermark Ever

Outputs are clean. We never stamp our brand or a paywall watermark on your files.

Free to Use

No accounts and no signup. Use the tool as much as you need within reasonable browser limits.

Works on Every Device

Windows, Mac, Linux, iPhone, iPad, Android, Chromebook. Any modern browser.

Built on Open Source

Powered by @cantoo/pdf-lib for local AES-256 password protection.

Common uses for password protect pdf

Confidential contracts

Open only to those who know the password.

Financial reports

Share with auditors but no one else.

Personal records

Protect tax docs before emailing.

HR documents

Salary letters, NDAs, internal memos.

Frequently asked questions

Is Password Protect PDF safe to use?

Yes. Everything happens in your browser. Your selected files are processed in your browser and are not uploaded to our server. Closing the tab clears the working session from this page; downloaded outputs remain on your device until you delete them.

Do I need to register or sign in?

No. No account, no email, no sign-up. Open the page and start using the tool immediately. Free to use, no signup needed.

Is there a watermark on the output?

No. PDF Tools Base never adds a watermark or branding to your output. Your final file is clean — just what you produced from the original.

Is there a file size limit?

Phones may struggle with PDFs over 50–100MB; desktops may handle larger PDFs but can still fail on very large or complex files. Large PDFs may be slow or fail depending on browser memory, page count, encryption type, and PDF complexity.

Does this work on mobile devices?

Yes. The tool works on all modern mobile browsers: Chrome on Android, Safari on iOS, Firefox, Edge, Brave. The drag-and-drop also accepts files from your phone’s file manager.

What if I forget the password?

There is no recovery if you forget it. PDF readers should require the password to open the output. Use a strong password and verify the downloaded PDF in your target viewer. Weak passwords can be guessed.

All product names, logos, and trademarks are the property of their respective owners. This is an independent tool and is not affiliated with, endorsed by, or sponsored by any of them.