PDF Password — Add or Remove

Is my file uploaded anywhere?

No. Both locking and unlocking run inside this browser tab using @cantoo/pdf-lib, which reads and rewrites the PDF entirely in memory. The password you type never leaves the page in a network request, and the download link is a blob URL your browser created locally, not a link to a server copy. Open your browser's developer tools, switch to the Network tab, and run either mode — you will see no upload, and the tool keeps working with the network disconnected.

That matters more here than on most tools on this site: the input is often something you specifically do not want a third party to see, and the whole point of a password is to control who can open it.

Can this tool crack a password I don't know?

No, and it does not try to. This is not a password-recovery tool. Removing a password requires typing the correct one; if you do not know it, this tool cannot help, and neither can any tool that respects the encryption standard PDF uses — brute-forcing AES-256 is not a browser-tab-sized problem. If you locked a file yourself and forgot the password, a password manager set up beforehand is your real option; otherwise the document is effectively gone. That is a property of encryption, not a limitation of this implementation.

What is the difference between the two passwords when locking?

The password to open the file ("user password") is what a reader is asked for before seeing any content — what most people mean by "a password-protected PDF." The owner password is optional and separate: it controls the permissions below (printing, copying, editing, commenting) for someone who already has the open password, but does not add a second barrier to opening the file. Leaving it blank is fine for most uses.

Owner passwords are also the weaker of the two in practice. They discourage casual permission changes rather than stop a determined reader — several PDF viewers ignore permission flags once a file is open. Do not rely on it alone to prevent printing or copying sensitive content; if that content must not be readable at all, remove it before export instead.

Why AES-256, and can I pick a weaker cipher?

The tool always encrypts with AES-256, the strongest cipher the PDF standard defines and the one every modern reader supports. Older, broken RC4 variants exist in the underlying library for viewers from before 2005, but are not exposed here — there is no reason to pick a cipher known to be crackable when the strong one opens in the same readers at no extra cost.

What happens when I remove a password?

The library cannot just re-save the decrypted document — that keeps the encryption dictionary and produces another encrypted file. Instead, once your password opens it, every page is copied into a brand-new, unencrypted document, and that copy is what gets downloaded. This is reliable for page content — text, images, layout — but anything not physically attached to a page does not come along: form fields, annotations and comments, the bookmark/outline tree, and document-level metadata like the author field.

If the file has fillable form fields, the tool checks before this step and shows a count first, so you can back out rather than discover the loss after downloading. Outline and metadata loss is not currently flagged up front — treat "remove password" as producing a flattened copy of the content, not a byte-identical file with the lock taken off.

I'm sure the password is right, but it says it's wrong

Check for a trailing space or an autocomplete substitution first — the most common cause. PDF passwords are case-sensitive, and unlike many login forms, most PDF-producing software does not normalize accented or non-Latin characters, so a password typed on a different keyboard layout than the one that set it can come out different. If someone else locked the file, confirm you were given the user (open) password and not an unrelated one they use elsewhere.