How to use it
- Drop the PDF you want to protect.
- Type an open password and confirm it.
- Optionally restrict printing, editing or copying.
- Click Protect PDF and save the encrypted copy.
When to password-protect a PDF
Email and cloud links get forwarded, misaddressed and left in shared folders. A password means only people who know it can open the file:
- Tax returns and financial statements sent to an accountant or lender.
- Medical records shared with a new provider or insurer.
- HR documents with salaries, reviews or Social Security numbers.
- Contracts and legal documents before they are signed.
- Client deliverables you want to keep private in transit.
Send the password through a different channel than the file, for example a text message or a phone call, so a single intercepted email does not expose both.
Open password and permissions
| Setting | Effect |
|---|---|
| Open password | Required to open the PDF at all. This is the real protection. |
| Restrict permissions | Controls printing (allowed, low quality only, not allowed), editing (allowed or not), copying text and images, and comments and form filling. |
| Owner password (optional) | Needed to change the permissions later. If you leave it empty, a random strong owner password is generated, so nobody can lift the restrictions with a blank password. |
You can use permissions without an open password: the PDF then opens for everyone, but the restrictions apply. The owner password must differ from the open password, or the restrictions would be meaningless.
A strength meter rates your open password. Aim for at least 12 characters mixing upper and lower case, numbers and symbols, or use a passphrase of several random words.
How strong is the encryption?
The file is encrypted with AES-256, the strongest encryption defined in the PDF standard (PDF 2.0 / ISO 32000-2) and supported by current PDF readers on Windows, Mac, iPhone and Android and by the PDF viewers built into major web browsers. With a strong password, the content cannot practically be read without it.
Permissions are different: they are honored by well-behaved PDF readers, but not every program enforces them. Treat restrictions as a polite request and the open password as the real lock.
Private: no upload
Encryption runs in your browser using qpdf, an open-source PDF library compiled to WebAssembly. Your PDF and your password never leave your device. The qpdf component (about 1.3 MB) downloads the first time you use the tool.
There is no password recovery. If you forget the open password, neither we nor anyone else can open the file for you, so store it in a password manager.
A worked example
You are emailing last year's tax return to a mortgage broker. Drop the PDF here, type a passphrase such as maple-river-lantern-42, confirm it, and click Protect PDF. You get return-protected.pdf. Email the file, then text the passphrase to the broker. If you also want to stop the broker's office from printing it, turn on Restrict permissions and set printing to Not allowed.
Related tools
- Already protected and need to change the password? Remove the old one with Remove PDF password, then protect it again.
- Want to hide specific details instead of the whole file? Use Redact PDF.
- Want a visible label? Watermark PDF adds CONFIDENTIAL to every page.
Frequently asked questions
How do I put a password on a PDF?
Drop the PDF, type and confirm a password, and click Protect PDF. The encrypted copy downloads right away.
What encryption is used?
AES-256, the strongest encryption in the PDF standard, supported by all current PDF readers.
Can I stop people from printing or copying my PDF?
Yes. Turn on Restrict permissions and choose the options. Note that not every program enforces these restrictions.
Is my password uploaded?
No. Encryption happens in your browser; neither the file nor the password leaves your device.
What if I forget the password?
It cannot be recovered. Keep the password in a password manager or another safe place.
Can I protect a PDF that already has a password?
Remove the existing password first, then add the new one.
Last updated: November 13, 2026