Protect PDF

Yes, and the reason is worth spelling out. Sending a private file to a website so that the site can lock it means handing over the document and the password together, to a server you cannot see. This tool never asks you to do that. Your PDF is read and encrypted right inside your browser, and the password you type is used on your device and then forgotten. That makes it a reasonable choice for payslips, medical letters, tax papers, and contracts.

The file is encrypted with AES-256 by qpdf, an open-source PDF tool that has been maintained for years and is compiled here to run in the browser. Your password is turned into a key, the contents of the document are encrypted with it, and the result is written as a normal PDF that any reader can open once the password is given. Nothing about the file is watered down because it happened in a browser instead of on a server.

One consequence is worth knowing before you start. Because the password never leaves your device, there is nothing on our side to look it up in. A lost password means a lost document.

The open password is the one people type to get in. Without it the document will not open at all. This is the one to use when the content itself is private.

The permissions password sits behind the advanced toggle and does a different job. Setting it lets you record limits inside the file, such as asking readers not to print it or not to copy text out of it. Anyone holding the permissions password can change those limits again; anyone holding only the open password reads the file with the limits in place. You choose both, on this page, and neither is stored anywhere.

If you leave the advanced section closed, you get an open password and nothing else, and everyone who can open the file has full rights inside it.

They are a request that is written into the file, and mainstream readers honour it. Acrobat, Preview, and Chrome will grey out the print button or refuse a copy when the file says so. Other tools ignore these flags entirely, and a determined reader can screenshot any page they can see.

So use them for what they are good at: stopping the accidental reprint of a controlled document, or making it clear that a draft is not meant to be lifted. When the content must not be read at all by the wrong person, the open password is the part that does the work.

Drop more than one file and the batch view opens instead of the editor. By default one password covers the whole set, which suits a folder of statements going to the same person. Turn on the per-file toggle and each file gets its own box, which suits payslips going to different people. The advanced permissions section is there in batch mode too, and the limits you set apply across the batch.

Each row is named after the file you will receive, so report-protected.pdf is the locked copy, not the one you dropped in. Every row has its own download button, and Download all as ZIP takes them together.

Protecting a PDF copies your pages rather than redrawing them, so almost everything survives. Here is the honest breakdown:

• Every page, at full quality, with text still selectable once the password is given.
• Images at their original resolution, and the page size and order you started with.
• Your original file, untouched on your device. Only the copy is locked.
• Any hope of recovery if you forget the password. There is no reset.
• Form fields and similar extras, but only on damaged files that had to be rebuilt before they would encrypt.

A few PDFs are refused by the encryption step because their internal index does not match what is inside them. Scanners produce files like this fairly often, and the file usually still looks fine in a reader. When that happens the tool rebuilds the document on your device and encrypts the rebuilt copy, so you get a protected file instead of an error.

Pages and images come through the rebuild unchanged. Interactive extras may not. If a file is damaged enough that even the rebuild is turned down, Repair PDF is the next thing to try.

Encryption is one of the cheaper things you can do to a PDF, because the pages are copied rather than redrawn. On a deliberately slow two-core test setup, a seven-page document of 368.0 KB was protected in well under a second, and a one-page scan of 1.01 MB took about the same. Your own device and file will differ, and a very large scan on an older phone is the case that takes noticeably longer.

Yes. It works in mobile Safari, Chrome, and other modern mobile browsers, with nothing to install. Add the file the same way, type the password twice, and the locked copy saves to your device. Typing a long password on a phone is easier to get wrong, so use Show to check it before you tap Protect PDF.

• Emailing a payslip or tax document to someone who should be the only reader.
• Sending bank statements to an accountant or a landlord.
• Locking a signed contract before it goes out to several people.
• Putting a password on medical letters or ID scans kept on a shared computer.
• Marking a draft as not for printing before it circulates internally.