Password Protect Your PDFs for Free Online

Protect PDF by password encrypts a PDF so it opens only after a reader enters the password you set, and returns that encrypted copy as a download. Page count is shown after upload to confirm the right file is attached before locking. Works in any modern browser, no install required.

This route writes a brand-new encryption envelope; it does not remove an existing one. If the PDF already requires a password you want to drop, use Remove PDF Password instead - you still need to know the current password to do that. There is no document signing here either: this page applies the single on/off open password that most readers mean when they say "add a password to this PDF".

One open password, no separate permissions lock

PDF security has two password concepts: a user password (open password) that blocks opening the file at all, and a separate owner password (permissions password) that some tools use to restrict printing or copying once the file is already open. This tool sets only the open password - the single password you type is required before any page renders, and it offers no second, different owner password. So once someone enters the password they can view, print, copy, and edit the file freely: keeping a document readable while blocking printing or copying is not possible here.

An owner password is also the restriction that blocks most signature tools, not the open password this tool applies. To sign a PDF that already carries one, remove it first with Remove PDF Password, then sign - see How to sign a PDF after removing its password for the order of operations.

Choosing a PDF password that resists common attacks

Target twelve characters or more, mixing cases, digits, and at least one punctuation mark. Avoid dictionary words, dates tied to the document, and strings derived from the filename. A passphrase of four unrelated words is the strongest memorable option. For archival documents, consider a second layer - a ZIP password blocks the byte-level file even before the PDF viewer runs. The encryption is a 128-bit key; since only one password exists here, that password - not the cipher - is the part worth making strong.

Privacy and how this tool handles the password you set

To encrypt the PDF, the file is uploaded over HTTPS to our processing service along with the password you enter. The service generates an encrypted copy and returns a download link. Files are removed after a short retention window.

Where a password stops and redaction starts

A password and a redaction solve different problems: the password on this page controls who can OPEN the file and can be removed later by anyone who knows it, while the Redact PDF tool permanently DELETES the marked content for every reader, with no way back. For a document that must circulate widely with certain lines removed, redact first - then encrypt the result here if access control is also needed.

Prep steps that pair with adding an open password

When the PDF is a filled-in form, run Flatten PDF before you encrypt it here, so the completed fields and annotations become permanent page content rather than editable form fields at the moment you add the password. For the background on the two password types, read PDF password types - owner vs user.

← Back to PDF Tools - merging the protected output with other documents, compressing the encrypted result before email, or flattening a form before re-locking it all sit on the same PDF tools hub.