Protect PDF with a password
Encrypt your PDF with a user-open password, an owner permission password, or both. Choose 128-bit or 256-bit AES encryption — applied locally, your file never touches a server.
or drop files here
Tip: select a single file.
How to use Protect PDF
- 1Click "Select PDF file" and choose the PDF you want to password-protect.
- 2Set an open password and optionally restrict printing or copying, then confirm the password.
- 3Click Protect PDF. The encrypted file is built in your browser and downloaded.
Why use PDF Lab
- Encrypt PDFs with a password and restrict printing or copying.
- Files stay on your device — nothing is uploaded to any server.
- No account, no signup, no watermark on the output.
- Free to use with no per-file limits beyond your device's memory.
- Works on desktop and mobile browsers, including offline after first load.
- Encryption is applied locally — your password never leaves your device.
- Set separate open and permissions passwords for fine-grained access control.
Your file never leaves your browser
Protect PDF runs entirely on your device using pdf-lib and pdf.js — both self-hosted by PDF Lab, so no third-party CDN sees your traffic. There is no upload, no account, no log of your file.
How browser-based PDF processing works →Protect PDF — questions
- No. Every operation runs in your browser using JavaScript. Your file is loaded into your browser's memory, processed, and a result is saved to your device. Nothing is sent over the network.
- No. Because the processing happens in your browser, neither PDF Lab nor any third party has access to the file contents. You can verify this by opening your browser's network tab while using the tools — no file data is transmitted.
- There is no enforced limit, but performance depends on your device's memory. Most modern browsers comfortably handle PDFs up to about 100 MB. Very large files may slow down your browser tab.
Are my files uploaded to your server?+
Can PDF Lab see the contents of my files?+
Are there file size limits?+
Related tools
Unlock PDF
Enter the password you know to unlock a protected PDF and save an unrestricted copy.
Sign PDF
Draw your signature with a mouse or finger, type it in your chosen font, or upload an image of your signature.
Redact PDF
Draw redaction boxes over sensitive content — names, numbers, addresses — and burn them into the PDF permanently.
Flatten PDF
Lock form fields, comments and annotations into the page permanently so the PDF cannot be edited further.
Edit Metadata
Update the hidden properties of any PDF: title, author, subject, keywords, producer and dates.
Add Watermark
Stamp a custom text or image watermark across every page.