Protect PDF with a password

How to password protect a PDF

1. Drop the PDF onto the box above, or click it to browse. One document at a time.
2. Type your password, then type it again underneath. The button stays disabled until the two match, and the small meter tells you whether what you have chosen is very weak, fair or strong — eight characters is the sensible floor.
3. Decide what readers may do once they are in. Printing and copying text are permitted by default; editing is not. Untick anything you would rather block. Filling in form fields and screen-reader access always stay allowed.
4. Press “Protect PDF”. The encrypted copy downloads with -protected added to the filename, and from then on Acrobat, Chrome, Edge, Preview and phone readers will all ask for the password before showing a single page.

What people use it for

Encryption is worth the small extra step whenever a file is about to travel through email, chat or a shared folder, where forwarding is easy and access lists drift over time.

• Emailing a payslip, a tax return or a bank statement to an accountant.
• Sending medical results or an insurance claim where the inbox is shared with a family member.
• Handing over a contract draft or a price list that should not circulate beyond one recipient.
• Archiving scanned ID documents, deeds or certificates on a laptop that leaves the house.
• Distributing a training manual you would rather readers did not edit and re-issue as their own.

Good to know

Write the password down somewhere safe before you close the tab. The file is encrypted with 128-bit AES using the password you typed, and that password is not stored — not in this page, not in a database, not anywhere. There is no reset link and no support address that can help: if you forget it, nobody, ourselves included, can open the document again. That is the honest trade for encryption that genuinely works.

Two practical points. A PDF that is already protected can still go in. One that opens freely but blocks printing, copying or editing is opened without a prompt; one that needs a password to open asks for it first, and that password is used only inside this tab. Either way the old protection is dropped and replaced by the password and permissions you choose here, and the page tells you when that has happened. And the permission tick-boxes are not a hard barrier. They are locked with a second, owner password — 32 random characters generated in your browser, never shown and discarded as soon as the file is saved — so mainstream readers such as Acrobat, Chrome, Edge and Preview respect the boxes you untick. But anyone who can open the file can read what is in it, and some viewers and freely available tools simply ignore the restrictions. Consider them a clear signal of intent rather than a lock — a visible watermark across the pages makes the same point rather more plainly. Since nobody knows that owner password, you included, keep your original file if you may need an unrestricted copy later. Everything happens inside your browser, and that is the whole point on this particular page: an upload-based site receives two secrets in the same request, the confidential document and the password meant to guard it. Here neither one leaves your computer, so there is nothing on anyone's server to leak.

Questions people ask

What kind of encryption is used?

128-bit AES (the AESV2 method from the PDF standard), applied to the document itself. Your password is the one that opens the file; the permission settings sit under a separate, random owner password that is thrown away once the file is saved. The result is a standard encrypted PDF that any modern reader understands (Acrobat has read it since version 7) — nothing proprietary and nothing that needs EditZap to open it later.

Can I remove the password again afterwards?

Yes, as long as you still know it. Unlock PDF strips it back off and gives you an ordinary file. It cannot help if the password has been forgotten.

Can I change the password on a PDF that already has one?

Yes. Drop the file in, type the new password twice and press “Protect PDF”. You are asked for the current password first; it is checked on your device to open the file, and the copy you download opens with the new one instead.

Does it work on a large or scanned document?

Usually, though very large scans are held in memory while they are encrypted, so an older phone may struggle where a desktop will not. Running Compress PDF first often makes the job comfortable.

How strong should the password be?

Long beats clever. Three or four unrelated words are easier to remember and harder to attack than a short string of substituted symbols. Avoid anything you have used elsewhere, and send it to the recipient by a different channel than the file itself.