How unlocking works
A password-protected PDF is encrypted: every page's text, pictures and fonts are scrambled with a key made from the password. The file also holds a small block, the encryption dictionary, that says which cipher was used. When you add a file, this tool reads that block to name the cipher, then tries to open the file with an empty password to find out which of two cases you have.
| What the tool finds | What you need | What you get |
|---|---|---|
| An open password (the PDF asks for it every time) | That password, or the owner password | A copy that opens without a password and has no restrictions |
| Only an owner password (opens freely, but printing or copying is blocked) | Nothing | A copy with the restrictions removed |
| No encryption at all | Nothing | Nothing to do: the file already opens anywhere |
With the right password, @cantoo/pdf-lib (an open-source PDF library, MIT licence) decrypts every part of the file and saves a new copy without the encryption dictionary. The tool then reads the new copy back to confirm it really is unencrypted before it downloads. The copy is named after the original with "-unlocked" added, so the protected original is not overwritten.
Worked example: a locked bank statement
Your bank emails "Statement_March.pdf", and every time you open it, it asks for a password. You add it here; the tool reports AES-256 and asks for the password. You type the one the bank gave you. A few seconds later "Statement_March-unlocked.pdf" is in your Downloads folder, with the same 4 pages, and it opens straight away in any PDF reader. It is now easy to attach to a loan application or merge with other documents.
Your password stays on your device
Most online unlock services upload your PDF to their server and ask you to send the password with it. Here, both stay in your browser tab: the decryption code runs on your computer or phone, and the page has no way to send the file anywhere. When you close the tab, they are gone.
What this tool will not do
It will not break or guess a password you don't have. A strong password on an AES-encrypted PDF can't be recovered in any practical time, and tools that claim otherwise only work by trying huge lists of likely passwords. If a PDF you are entitled to read is locked and you don't know the password, ask whoever sent it. Removing protection from documents you aren't authorized to open or change can break the law or a contract, so only unlock files that are yours or that you have permission to change.
To put a new password on the unlocked copy later, use Password protect PDF.
Questions people ask
Can it remove a password I don't know?
No. This tool never guesses or cracks passwords. To open a file that asks for a password you have to type that password, exactly as it was set, including capital letters. If you have forgotten it, the person or company that sent the file can send it again, or tell you the password. Banks and payroll services that email locked statements usually explain the password format in the same email.
My PDF opens fine, but I can't print it or copy text from it. Can this fix that?
Yes. That file has an owner password that only sets restrictions (no printing, no copying, no editing). It has no open password, so this tool can remove the restrictions without asking you for anything. Do this only for documents you are allowed to print or edit, such as your own pay stubs or tax forms.
Which kinds of PDF protection does it handle?
Standard password security in all four common strengths: RC4 40-bit, RC4 128-bit, AES-128 and AES-256. It accepts either the open password or the owner password. It cannot open files protected with a digital certificate instead of a password, or files under company rights management (DRM) that check with a server before opening.
Is my file or password uploaded?
No. The page loads its code once, then reads the file and decrypts it inside your browser. The PDF and the password you type stay on your device and are not sent anywhere. You can check by loading the page, turning off Wi-Fi, and unlocking a file.
Will the unlocked copy look different?
No. Pages, text, images, links and form fields are kept. The file is rewritten without encryption, so a digital signature on the original will show as invalid or changed in the unlocked copy. Keep the original if the signature matters.