How to Password-Protect a PDF File
Sending a sensitive contract, invoice or report? Adding a password keeps it safe from anyone who should not see it. KOIAE's Protect PDF tool encrypts your PDF with a password of your choice — free and online.
How to password-protect a PDF
- Open the Protect PDF tool. Visit the KOIAE Protect PDF page.
- Upload your PDF. Drag and drop the document you want to secure.
- Set a strong password. Choose a password that is hard to guess and easy for you to remember.
- Download the protected PDF. Download your encrypted, password-protected file.
Tips for the best results
- Use a mix of letters, numbers and symbols for a strong password.
- Store your password safely — without it the file cannot be opened.
- Share the password through a separate channel from the file itself.
Why use KOIAE Protect PDF?
KOIAE Protect PDF is completely free — there is no account to create, no watermark on your files and no daily limits for everyday use. Most processing happens right in your browser, so your documents stay private, and it works on any device from Windows and Mac to Android and iPhone.
Frequently asked questions
What encryption is used?
KOIAE applies standard PDF encryption so the file requires your password to open.
Can I remove the password later?
Yes, use the Unlock PDF tool with the password to remove it.
Is it free?
Yes, protecting a PDF with KOIAE is free and adds no watermark.
Related tools: Unlock PDF · Watermark PDF · Merge PDF · All PDF tools