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. Upload the file, type a passphrase, click Protect - the tool returns an encrypted copy. Page count is shown after upload to confirm the right file is attached before locking.

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. No document signing, no permissions matrix - just the on/off open password that most readers mean when they say "add a password to this PDF". Works in any modern browser, no install required.

User password vs owner password: what each one actually restricts

PDF security has two password concepts and they do different jobs. A user password (open password) blocks opening the file at all; the reader must enter it before seeing any content. An owner password (permissions password) can restrict actions like printing or copying after the file is open. This tool sets the open password only - the lock that requires a password before any page renders. It does not set an owner / permissions password.

Signing a PDF that already has an owner password? That is the restriction that blocks most signature tools, not the open password this tool applies. 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 envelope is industry-standard AES; the breakable link is the human-typed passphrase in front of it.

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.

Need the inverse workflow? To remove the password from a PDF you're allowed to open, use Remove PDF Password (you still need to know the password). If you're encrypting a form-filled document, run Flatten PDF first so filled fields and annotations become part of the final page content before the password layer is applied.

Unsure which password you are setting? Read PDF password types - owner vs user for the distinction most PDF tools leave unexplained: the user password blocks opening; the owner password blocks copy/print even after the file is open. Picking the wrong one is the single most common PDF-security mistake.

← 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.