PDF Toolkit

Protect PDF Online Free

Add password protection to your PDF documents securely in your browser.

About This Tool

Password-protecting a PDF is the easiest way to secure sensitive documents before sharing them. With PDF Toolkit's free Protect PDF tool, you can apply strong 128-bit AES encryption to any document directly in your browser. Whether you are sending financial reports, legal agreements, medical records, or personal documents, adding a password ensures only authorized recipients can view the contents. Since all encryption happens locally on your device using WebAssembly, your files are never uploaded to our servers, giving you complete privacy and peace of mind. Simply upload your PDF, choose a secure password, and download the encrypted file immediately.

How to Use

  1. 1

    Click "Drop PDF here" or click the upload area to select your document.

  2. 2

    Enter a strong password in both the Password and Confirm Password fields.

  3. 3

    Click "Protect & Download". The encryption process is instant and entirely local.

  4. 4

    Your password-protected PDF will download automatically. You can also save it to your account history.

Frequently Asked Questions

Is it safe to encrypt PDFs online?+
Yes! PDF Toolkit encrypts your files locally in your browser. Your documents are never uploaded to our servers.
What happens if I forget my password?+
The encryption is very strong (128-bit AES). If you lose the password, the PDF cannot be recovered or unlocked.
Can I protect large PDF files?+
Yes, this tool supports PDF files up to 20MB.
Does encryption affect the quality of my PDF?+
No, encryption only locks the file. All text, images, and formatting remain exactly as they were.

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Want to learn more? Read our PDF guides and tutorials →