Protect PDF with a Password
Lock a PDF so it only opens with your password, and decide what readers may do once it is open.
Drop a PDF here
or click to browse
Files are processed on your device and never uploaded.
Works in your browser. No account needed.
Frequently asked questions
How strong is the encryption?
The file is encrypted with AES-256, the strongest method the PDF standard defines and the one Adobe Acrobat uses for its highest security setting. With a long, unique password it cannot realistically be broken; with a short or common one it can be guessed, so the password matters more than the algorithm.
What if I forget the password?
Then the file cannot be opened, by you or by us. Nothing is uploaded and no copy is kept, so there is no reset link and no recovery. Keep your original unprotected file, or store the password in a password manager before you send the protected copy.
What is the difference between the open password and the owner password?
The open password is needed to view the document at all. The owner password is for the person in charge of the file: entering it instead of the open password gives full access regardless of the print, copy and edit settings. Leave it empty and a random owner password nobody knows is used.
Do the print and copy restrictions really stop people?
Readers that follow the PDF standard, such as Adobe Acrobat and Reader, honour them. They are not a hard lock: anyone who can open the file can print it to an image or use software that ignores the flags. For anything sensitive, rely on the open password and on who you give it to.
Will the protected PDF open on phones and in other apps?
Yes. AES-256 is part of the PDF standard and supported by Adobe Reader and Acrobat, Apple Preview and iOS, Android viewers and every major browser’s built-in viewer. Software older than roughly 2010 (Acrobat 9 and earlier) may not support it and will fail to open the file.
Is my PDF uploaded to a server?
No. The encryption runs in your browser using a self-hosted WebAssembly build of the open-source qpdf engine, loaded only when you click Protect. Your document and your password never leave your device.
About this tool
A password on a PDF is the simplest way to send something private by email or put it on a shared drive: payslips, contracts, medical letters, tax returns, scanned passports. This tool adds an open password to any PDF, so nobody can see a page without typing it. The document is encrypted with AES-256, the strongest encryption the PDF standard offers, and the result opens in Acrobat, Preview, phone viewers and browsers after asking for the password.
You can also set permissions. Untick Print, Copy or Edit and readers that follow the standard will block those actions even after the file is opened. Add an owner password if you want to lift them later; leave it blank and a random one is generated so that nobody holds it. Be realistic about permissions: they are instructions to well-behaved software rather than a hard barrier, so treat the open password as the real protection.
The protection is only as good as the password and how you share it. Use a long passphrase rather than a short word, avoid anything guessable such as a birth date, and send the password through a different channel from the file — a text message or a phone call rather than the same email. Keep your original file too: there is no way to recover a forgotten password, because nobody but you ever sees it.
Unlike most online PDF protectors, this one never uploads your document. The encryption engine is qpdf, a widely used open-source PDF library, compiled to WebAssembly and served from this site; it downloads the first time you protect a file and runs entirely on your device. That means the unencrypted file never passes through anyone else’s server — which is rather the point when the reason you are protecting it is that it is private. To remove a password you know, use Unlock PDF.