Protect PDF — Add Password Encryption
Lock your PDF with AES-256 encryption. All processing happens in your browser — your file and password never leave your device.
Drop your PDF here to protect
or click to select
Maximum file size: 100 MB
How PDF Password Protection Works
- Upload your PDF — Select the PDF you want to protect.
- Set a password — Choose a strong password (4+ characters).
- Download — Get your AES-256 encrypted PDF. Only people with the password can open it.
Why Client-Side Encryption?
Unlike most "free PDF tools" that upload your file to a server for encryption, PDF Toolbox uses the pdf-lib library to encrypt PDFs directly in your browser. This means:
- ✅ Your file never leaves your device
- ✅ Your password is never transmitted anywhere
- ✅ AES-256 encryption — same standard used by banks
- ✅ No registration, no limits, no uploads
⚠️ Important
PDF password protection is not uncrackable. For maximum security, use a long, unique password. There is no way to recover a lost password — store it securely (e.g., in a password manager).