Protect PDF — Add a Password, Block Printing
Browser tool that encrypts a PDF with AES-256 and an open password and/or permission restrictions
Runs in your browser · nothing is uploaded
Drop the PDF to protect here
One PDF (up to 100 MB). The file and the passwords never leave your browser.
What it does
Before you email a contract, a payslip or anything with personal details, lock the PDF so only the right person can open it. An open password is asked every time the file is opened. Restrictions can block printing, copying content, editing, adding comments and inserting or deleting pages. Use either one or both.
Encryption runs inside your browser with a downloaded PDF engine. The file and the passwords never travel over the internet, so it is fine for sensitive documents.
How to use
- Drop one PDF on the box or press Choose PDF. The first time, the PDF engine (about 1.3 MB) is downloaded from this site.
- Type an open password and repeat it. Leave it empty to add restrictions only.
- Under Restrictions, untick what to block, or set printing to “Low resolution only” or “Not allowed”.
- If anything is restricted, set a permissions password. It must differ from the open password.
- Press Protect and save and download
name-protected.pdf.
How it works
- Encryption: AES-256 only (PDF 2.0, security handler revision 6). The older RC4 scheme is easy to break and is not offered.
- Engine: qpdf 12.2.0 (Apache-2.0) compiled to WebAssembly. Pages, text, links and bookmarks are kept; only encryption is added.
- Password characters: any language and emoji work. Passwords are normalised to Unicode NFKC, as the standard recommends.
- Empty permissions password: when nothing is restricted, a random permissions password nobody knows is used. With no restrictions it is never needed.
- Screen readers: text extraction for accessibility is always allowed, as PDF 2.0 requires.
- Already encrypted files are not encrypted again; remove the old protection with Unlock PDF first.
- Limit: one file up to 100 MB.
Examples
| Goal | Settings |
|---|---|
| Payslip sent by email | Open password only, no restrictions |
| Handout that must not be edited or copied | No open password, copying and editing unticked, permissions password |
| Confidential contract | Open password + printing “Not allowed” + copying unticked + permissions password |
| Screen-quality printing only | Printing “Low resolution only” + permissions password |
To remove a password from a file you received, use Unlock PDF. To black out personal details before sending, run Redact PDF first.
FAQ
Are my file or passwords sent to a server?
No. The PDF engine (qpdf) is downloaded to this page and encrypts the file inside your browser. Nothing is uploaded, so this site never sees your password.
What if I forget the password?
It cannot be recovered. AES-256 is designed so the file cannot be opened without the password, and this site cannot open it for you either. Write the password down and keep your original file.
What is the difference between the open password and the permissions password?
The open password is asked every time the file is opened. The permissions (owner) password lifts restrictions such as no printing, so it must differ from the open password. You can set only an open password, only restrictions, or both.
Does "no printing" make printing impossible?
Most PDF viewers honour restrictions, but they are a rule the viewer agrees to follow and some programs ignore them. Add an open password when the content must stay private.
Which programs can open the result?
It uses AES-256 from the PDF 2.0 standard (ISO 32000-2), which Adobe Acrobat Reader and the PDF viewers built into Chrome, Edge and Firefox open. Very old viewers may not.
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