Add password protection to your PDF files. Secure your documents with encryption. Free and no sign-up.
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Max 50MB • Single file
Choose a strong password. You'll need this to open the PDF.
🔒 Security Information:
Your PDF will be encrypted with AES-256 encryption. The password is required to open the file.
Select the PDF file you want to protect with a password
Enter a strong password to encrypt your PDF
Get your password-protected PDF file instantly, no sign-up needed
We encrypt your PDF using AES-256 encryption. When someone tries to open the PDF, they'll be prompted to enter the password you set. Without the password, the PDF cannot be opened.
Use a combination of uppercase and lowercase letters, numbers, and special characters. Avoid common words or personal information. The longer the password, the more secure it is.
Yes, you can use our Unlock PDF tool to remove the password if you know it. Simply upload the protected PDF and enter the password to unlock it.
Unfortunately, if you forget the password, there's no way to recover it. The encryption is designed to be secure, so we cannot access your PDF without the password. Make sure to save your password in a secure place.
Upload your PDF (up to 50MB), type the password you want to use, and click "Protect PDF". BlendPDF encrypts the file with AES-256 and gives you a protected copy to download. No account or email is required.
BlendPDF encrypts your PDF with AES-256, the strongest encryption level defined in the PDF standard, using the qpdf engine. The password you set is required to open the file in any PDF viewer.
Yes. Uploads travel over an encrypted HTTPS connection, your password is used once to encrypt the file and is never stored, and files are deleted from our servers within one hour, most immediately after processing. We never read, store, or share document contents. We only collect aggregate, anonymous usage analytics.
Yes, it is completely free. There is no watermark, no page limit, no daily quota that pushes you to a paid plan, and no premium tier. The protected file you download is your document, unchanged except for the encryption.
No. You can protect a PDF without creating an account or entering an email address. An optional email-delivery feature exists if you want the file sent to your inbox, but downloading directly never requires an email.
No. If the PDF is already encrypted, the tool returns an error asking you to unlock it first. Use the Unlock PDF tool with the current password, then protect the unlocked file with your new password.
Not separately. BlendPDF sets an open password: nobody can open the file without it. It does not currently offer print-only or copy-only restrictions, and anyone who knows the password can use the document normally once it is open.
One PDF per operation, up to 50MB. If your file is larger, run it through the Compress PDF tool first and then protect the compressed copy.
No. Encryption wraps the existing content without re-rendering it. Text, images, fonts, links, and layout are unchanged, and the file size stays roughly the same.
Any reasonably modern PDF viewer can open AES-256 protected files, including Adobe Acrobat Reader, macOS Preview, Chrome, Edge, Firefox, and the standard iOS and Android viewers. Only very old software from before roughly 2010 may fail to open AES-256 files.
The encryption result is equivalent: all three can produce AES-256 protected PDFs. Adobe Acrobat Pro requires a paid subscription and offers extra permission controls; Word can only protect documents it exports itself. BlendPDF is free, works on any existing PDF, and needs no installation or account.
Check that the file is a valid PDF under 50MB and not already encrypted. If you see a "too many requests" message, wait a few minutes; protection is limited to 20 files per 15 minutes per user. If a valid file still fails, it may be corrupted; try the Repair PDF tool first.