Business
Protect PDF
Add a password to a PDF before you send it.
A payslip, a medical letter, a contract with someone else's details on it — anything you are about to email deserves a password if the inbox at the other end is not guaranteed to be private.
This applies the standard PDF encryption scheme (the same RC4-based Standard Security Handler most PDF software has supported for over two decades) directly in the browser: it re-derives the file's internal structure, encrypts every string and stream, and writes a password requirement into the file itself. Any PDF reader — Acrobat, Preview, browser viewers — will ask for the password before showing a page.
How to use it
- Choose the PDF you want to protect.
- Type a password and confirm it — at least 4 characters.
- Press Protect, then Download the encrypted file.
- Send the file and the password separately — by text message rather than in the same email, ideally — so intercepting one does not hand over both.
Questions
Can the password be recovered if I forget it?
No, and that is the point. The password is not stored anywhere — not by this tool, not in the file in a reversible way. If it is lost, the PDF is unreadable, same as any properly encrypted file.
How strong is this encryption?
It uses 128-bit RC4 under the PDF Standard Security Handler (revision 3), the same protection level Adobe Acrobat has offered for many years and that every mainstream PDF reader supports. It stops casual and moderately determined access; it is not the newer AES-256 scheme used for the highest-security documents, so do not rely on it alone for classified material.
Does this upload my file to check the password strength or anything else?
No. The PDF is read into the tab, encrypted with the password you typed, and handed back to you as a download. Nothing about the file or the password is sent anywhere.