How to Password Protect a PDF (Free)
Sending contracts, payslips, or personal documents by email? A password keeps them private even if the file ends up in the wrong inbox. PDFBuild's free Protect PDF tool adds a password to your PDF online. The file is encrypted on the server and deleted immediately afterwards.
How to do it — step by step
- Open the Protect PDF tool and upload your PDF.
- Type a strong password — mix letters, numbers, and symbols.
- Confirm the password and click Protect.
- Download the encrypted PDF.
- Try opening it to verify the password prompt appears.
Tips for the best result
- Use a password at least 12 characters long; avoid birthdays and simple words.
- Share the password through a different channel than the file — for example, send the PDF by email and the password by message.
- Keep an unprotected copy somewhere safe in case you forget the password — it cannot be recovered.
- Remember where you saved the password; PDFBuild cannot unlock a file whose password you've lost.
Frequently asked questions
Is password-protecting a PDF free?
Yes — free, no signup, and no watermark added to your file.
What encryption is used?
The PDF is encrypted with strong, standard PDF encryption, so it prompts for a password in any PDF reader.
Is my file stored on the server?
No. It is encrypted and deleted immediately — nothing is kept.
What if I forget the password?
There is no way to recover it. Always keep a backup of the unprotected file or store the password safely.
Can I remove the password later?
Yes — use the Unlock PDF tool with the password you set.