How to Password Protect a PDF for Free
Add a password so only the right people can open your PDF.
Sensitive documents deserve a password. Encryption locks the PDF so it cannot be opened without the key.
ChangeMyPDF runs entirely in your browser — your files never leave your device, there's nothing to install, and you can start without an account. Here's exactly how to do it.
Step-by-step
- Open the Protect PDF tool and add your file.
- Type a strong password (and confirm it).
- Apply 128-bit encryption.
- Download the protected PDF.
Tips for the best result
- Use a password you can share securely.
- Store the password in a password manager.
Is it safe and free?
Yes. Most ChangeMyPDF tools process files locally in your browser, so documents are never uploaded to a server. Free accounts can run a few operations per hour; a Week Pass or Premium plan removes the limit and ads if you need to do more.
Frequently asked questions
What encryption is used?
128-bit RC4, which every major PDF reader can open with the password.
Do my files get uploaded to a server?
For most tools, no — the work happens in your browser, so your documents stay on your device.
Is it really free?
Yes. Free users get a few runs per hour. For unlimited use and no ads, grab a $5 Week Pass or a Premium plan.
Which browsers are supported?
Any modern browser — Chrome, Edge, Firefox, and Safari on desktop and mobile.