Protect PDF Online for Free
Lock any PDF with a password using strong AES-256 encryption on ToolMint. Set the open password viewers will need to access the file, and optionally restrict permissions such as printing and copying — all without uploading to any server.
PDF Security
Protect PDF
Add password protection with AES-256 encryption and control viewer permissions.
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Drop your PDF here
Upload one PDF to lock it with a password.
Settings
Protect PDF uses the bundled native pdfcpu engine with AES-256 encryption. Your file is processed on the server and the protected PDF is returned for download.
How to Password-Protect a PDF
1
Upload a PDF
Select the PDF you want to password-protect.
2
Set a password
Enter the open password required to view the protected file.
3
Choose permissions
Optionally restrict printing, copying, or editing by setting permission flags.
4
Download
Download the AES-256 encrypted PDF ready to share securely.
Frequently Asked Questions
- What encryption standard is used?
- ToolMint applies AES-256 bit encryption, which is the industry standard for securing PDF documents.
- Can I restrict printing or copying as well?
- Yes. The permissions panel lets you individually restrict printing, copying text, and modifying the document.
- What happens if I forget the password?
- There is no way to recover a forgotten password — keep it somewhere safe. If you lose it, the file cannot be decrypted.
- Can I protect a PDF that is already encrypted?
- You need to unlock the existing encryption first using the Unlock PDF tool, then re-protect with a new password.
- Is my PDF sent to a server?
- No. Encryption is performed entirely in your browser using WebAssembly. Your file never leaves your device.