To password-protect a PDF, open Protect PDF, drop your file, set a password, and download the encrypted copy. The encryption runs entirely in your browser, so neither your document nor your password is ever sent to a server — a real advantage over cloud tools that receive both.
Why protect a PDF locally matters
Password-protecting a PDF is exactly the kind of task where uploading is self-defeating: the whole point is confidentiality, yet most online tools send your sensitive file (and the password) to their servers. Doing it on your own device keeps the secret a secret.
How to add a password
- Open Protect PDF and drop your PDF.
- Type the password you want to require.
- Click Protect and download the encrypted PDF — any reader will now prompt for the password.
Removing a password you know
Need to drop the password from a PDF you can already open? Use Unlock PDF with the current password to save an unprotected copy. (You must know the password — this isn't a way to bypass protection you don't have rights to.)
Related: mark documents as confidential
To visibly flag a document without encryption, add a stamp with Watermark PDF — "CONFIDENTIAL" or "DRAFT" across every page, also done in your browser.
What a PDF password actually protects
The password you set is an open password: the file is encrypted, and no reader will show a single page without it. That is real protection for a document sitting in an inbox, on a shared drive, or on a lost laptop — someone who copies the file gets ciphertext, not your contract.
What it does not do is control the person you gave the password to. Once they can open the document they can read it, screenshot it, and usually re-save it without protection. Encryption protects a file in transit and at rest; it is not a way to lend someone a document and take it back. Protect PDF also leaves printing and copying enabled and disallows modification — those permission flags are advisory, and well-behaved readers honour them while others ignore them, so never rely on permissions alone for anything sensitive.
Choosing and sending the password
Pick something long rather than something clever. Encrypted PDFs can be attacked offline at high speed, so a short password on a document that leaks is a delay, not a defence. Three or four unrelated words are easy to relay over the phone and far harder to crack than a mangled single word.
Send the password through a different channel from the document. Emailing a protected PDF and then emailing the password puts both in the same mailbox, which undoes most of the benefit — send the file by email and the password by text or a call. And keep an unprotected original somewhere safe: a password you cannot remember is indistinguishable from a file you have lost, because there is no recovery path.