How to use Protect PDF
- Select the PDF.
- Enter the password twice. Optionally block editing and copying.
- Click “Protect PDF” and download the encrypted file.
Strong, standard encryption
bopdf uses qpdf (compiled to WebAssembly) to apply 256-bit AES encryption, the strongest standard PDF security, supported by Adobe Reader, Preview, Chrome, Edge and every modern viewer.
Choose a long password and keep it safe: there is no way to recover it. To remove the password later, use Unlock PDF.
🔒 Your files never leave your device
bopdf processes your documents locally with JavaScript (pdf-lib and Mozilla pdf.js) inside your browser tab. Your PDF is never uploaded, stored or seen by us — you can even disconnect from the internet after the page loads and the tool keeps working. When you close the tab, everything is gone.
Frequently asked questions
How secure is it?
AES-256 is the strongest encryption the PDF standard offers; security depends on your password length.
Can bopdf see my password?
No, encryption happens in your browser.
Are my files uploaded to a server?
No. Everything happens in your browser on your own device. Files are never sent over the internet, which makes bopdf suitable for confidential documents.
Is there a file size limit?
There is no fixed limit, but very large files (hundreds of MB) depend on your device memory. On phones, files up to about 100 MB usually work well.