Protect PDF: how it works
To password-protect a PDF, open the Protect PDF tool, add your file, set a password, and download an AES-encrypted copy. Encryption is applied in your browser and the file is never uploaded.
How to use Protect PDF
- Open the Protect PDF tool and add your PDF.
- Enter a strong password.
- Download the encrypted PDF.
In your browser vs. uploading to a server
Best for securing a sensitive document before emailing it. PDFER applies AES encryption locally, so the unprotected file never leaves your device.
Frequently asked questions
How do I add a password to a PDF?
- Open the Protect PDF tool, set a password, and download; the PDF is AES-encrypted in your browser so it can only be opened with that password.
What encryption does it use?
- PDFER encrypts with AES-256, the standard used by professional PDF software, applied entirely on your device.
Are my files uploaded to a server?
- No. PDFER runs entirely in your browser using WebAssembly and JavaScript. Your files are read into memory on your device, processed locally, and never sent to PDFER or any third party. Closing the tab or leaving the tool erases them from memory.
PDFER is a privacy-first PDF toolkit built by Kiril Urbonas. Every tool runs entirely in your browser — see our security model and privacy policy.