Protect PDF

Add a password to a PDF, encrypted with AES-256.

Select a PDF to protect

Click to choose, or drop a file here

About password-protecting a PDF

Adding a password means the file can't be opened without it — a basic layer of protection when emailing something confidential or storing it in shared cloud storage.

The encryption is applied in your browser and the protected file is what you download; the password is never sent anywhere. Keep a copy of the password somewhere safe, because a protected PDF genuinely cannot be opened without it, and share it through a different channel from the file itself.

How to Protect PDF

1
Open the tool
Open the Protect PDF tool and drop your file onto the page, or click to browse for it. Everything runs in your browser — the file is never uploaded.
2
Set a password
Type the password you want to require to open the file.
3
Encrypt and download
Click Protect and download the AES-256 encrypted PDF.

Related PDF tools

Fill & Sign PDFFill in a PDF form and sign it — type text, tick boxes, add dates, drop your signature and initials anywhere.Sign PDFDraw or type a signature and place it on the page.Redact PDFBlack out and permanently flatten sensitive areas.Unlock PDFRemove a known password from a PDF.

Protect PDF — frequently asked questions

What encryption does this actually use?+

AES-256, the current PDF encryption standard — the same class of encryption Adobe Acrobat and other professional tools use, applied entirely in your browser via the Web Crypto API.

Can I recover the password if I forget it?+

No — there's no recovery mechanism, by design. That's what makes the encryption real. Keep the password somewhere safe; if it's lost, the file can't be opened by anyone, including you.

Do you upload my files to a server?+

No — every tool here processes your files entirely on your device, and nothing is uploaded to a server. The only exception is the AI tools, which send the extracted text (not the file) to Claude to do their work.

Is there a file size limit?+

There's no artificial limit we impose, but since processing happens in your browser, very large files (500+ MB or 1,000+ pages) are limited by your device's memory rather than by us.