Password-protect a PDF.
To password-protect a PDF for free, open it below, set a password, and click Protect PDF. It’s encrypted with AES-256 right in your browser — your file and your password are never uploaded.
How to password-protect a PDF
- 1
Open your PDF
Drop the PDF you want to lock into the box above, or click to browse. It stays on your device.
- 2
Set a password
Choose a password and confirm it. Plume encrypts the file with AES-256 — the strongest standard PDF encryption.
- 3
Download
Save the protected PDF. From now on it can only be opened by entering your password.
Plume vs upload-based tools
Most “free” online PDF tools send your files to a server. Plume never uploads them at all.
| Feature | Plume | Upload-based tools |
|---|---|---|
| Where files are processed | In your browser | Uploaded to a server |
| Do files leave your device? | Never | Yes (“deleted later”) |
| Sign-up | None | Often required |
| Watermark | None | On free tiers |
| File size / count limit | Only your device’s memory | Free-tier caps |
| Works offline | Yes (after load) | No |
| Price | Free | Freemium |
More PDF tools
Every tool runs the same way — privately, in your browser.
Encryption happens inside your browser — your file and password are never uploaded. Remove a password
Questions, answered
How do I password-protect a PDF for free?+
Open your PDF above, choose a password and confirm it, then click Protect PDF. The file is encrypted with AES-256 entirely inside your browser and downloads instantly — no sign-up, no watermark.
What encryption does Plume use?+
AES-256 — the strongest standard PDF encryption, the same algorithm Adobe Acrobat uses. The password becomes both the open and owner password, so the file is fully locked.
Are my file and password uploaded anywhere?+
No. The encryption runs entirely in your browser. Your PDF and your password are never sent to a server — you can even protect a file with your wifi switched off.
What happens if I forget the password?+
It can't be recovered. Because everything happens on your device, we never see your password and have no way to reset it — so store it somewhere safe, like a password manager.
Will the protected PDF open on other apps and phones?+
Yes. AES-256 protected PDFs open in Adobe Acrobat, Apple Preview, Chrome, and mobile readers — anyone with the password can open it normally.
Is it free, with no limits?+
Yes — unlimited, no sign-up, no watermark and no file-size limit.