Candid Tools

Protect PDF

Protect PDF adds a password to a PDF with AES-256 encryption using pdf-lib in your browser, so neither the document nor the password leaves your device.

Drag and drop, or click to upload a PDF

PDF file · processed on your device, never uploaded

At a glance

Accepts
One PDF file plus the password to set
Outputs
An AES-256 encrypted PDF named <file>-protected.pdf
Where it runs
Entirely in your browser, on your device
What leaves your device
Nothing - the file never leaves your device, and neither does the password
Limits
No size or count cap; bounded by your device's memory
Account
Not required - there is no sign-up
Price
Free, with no watermark and no usage cap
Made by
Visrut
Last updated
8 October 2026

Drop in a PDF, choose a password, and download a copy that requires it to open - no Adobe Acrobat or other software required. It is encrypted with AES-256 entirely inside this browser tab; the file and password are never uploaded to a server.

How to use it

  1. Drag and drop, or click to upload, your PDF.
  2. Enter the password you want to protect it with.
  3. Click "Protect PDF" to encrypt it.
  4. Download the protected PDF - the file and password never leave your browser.

Frequently asked questions

Is my PDF or password uploaded anywhere?

No - encryption happens entirely in your browser using pdf-lib. Nothing is sent to a server.

What encryption does this use?

AES-256, the modern standard for PDF password protection.

What if my PDF already has a password?

This tool is for adding protection to a PDF that doesn't already have one. Remove the existing password first if you need to replace it.

What happens if I forget the password?

There's no recovery - write it down somewhere safe. Forgetting it means losing access to the protected PDF, the same as with any encrypted file.

Can I restrict printing or copying separately from the open password?

Not yet - this sets a single password required to open the file, without separate permission restrictions.

What's the protected file called?

Your original filename with -protected added, like report-protected.pdf.