Password-protect a PDF
Lock your PDF with strong AES-256 encryption; your password never leaves your device.
or drop it here · it never leaves your device
Processed in your browser. Your files are never uploaded. How we know
How to password-protect a PDF
Adding an open password means nobody can read the PDF without it, which is useful when emailing payslips, medical letters, tax returns or anything else that might be forwarded to the wrong person or left in a shared folder. Because the encryption runs in your browser, neither the document nor the password is ever sent to a server, so you aren’t trusting a website with the very thing you’re trying to protect.
- 1
Open your PDF
Choose the file to protect.
- 2
Set a password
Enter it twice, or use Suggest a strong password. Set permissions if you like.
- 3
Download
Save the encrypted copy and keep the password safe.
Protect PDF features
- AES-256 encryption
- Open password with a live strength hint
- Suggest a strong password in one click
- Optional permissions for printing, copying, editing and form filling
- Separate permissions password, or a long random one if you leave it blank
- Encryption checked before you download
How PDF encryption works in your browser
Encryption runs on your device using qpdf, a long-established open-source PDF library, compiled to run in the browser. Your file and password stay in this tab.
The PDF is encrypted with AES-256, the strongest method the PDF standard offers and one that current PDF readers support. Before handing you the file, we check that it really is encrypted and opens with your password.
You can also choose what people may do once it’s open: printing, copying text and images, editing, and filling in forms. These permissions are protected by a separate permissions password. Leave that blank and we set a long random one nobody sees, so the restrictions can’t be lifted later. Bear in mind that permissions are honoured by compliant readers only; the open password is what keeps the content private.
Sending a payslip by email
Open payslip-october.pdf and type a passphrase such as maple-orbit-lantern-42; the strength hint confirms it’s a good choice. Confirm it, leave permissions as they are, and download payslip-october-protected.pdf. Email the file, then send the password by a different route, such as a text message or phone call. That way, someone who only sees the email can’t open the attachment.
Good to know
- A phrase of three or four random words is both strong and memorable. Very common passwords are flagged as you type.
- We never see your password, so we can’t recover it. Store it in a password manager.
- Already-protected PDFs must be unlocked first with Unlock PDF, using the existing password.
- Want to mark a document visibly rather than lock it? Add a watermark.
Related tools and guides
Protect PDF: frequently asked questions
What does AES-256 mean?
It’s the Advanced Encryption Standard with a 256-bit key, the strongest encryption the PDF format supports. Without the password, the contents are unreadable.
What if I forget the password?
We never see or store it, so it can’t be recovered. Keep it somewhere safe, such as a password manager.
Do permissions stop copying or printing?
Only in PDF readers that respect them, and many do. They aren’t strong protection; the open password is what really protects your document.
Will the recipient need special software?
No. Any current PDF reader, including those built into browsers and phones, will ask for the password and open the file.
Is my password sent anywhere?
No. It’s used in this browser tab to encrypt the file, then discarded. It isn’t stored, logged or sent.