Password protect a PDF
Lock a PDF with a password and AES-256 encryption, without uploading the file you are trying to keep private.
- Nothing is uploaded
- Works offline after first use
- Open source
- No watermark · limit is your device’s memory; phones hold less
Adds a password to a PDF with AES-256 encryption and saves the protected PDF. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The size limit is your device’s memory, and phones hold less; give the page a short while after your first run to save itself for offline use, and then it works offline.
Done
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Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
How it works
- Drop one or more PDFs.
- Type the password twice.
- Save the protected copies. Anyone opening them is asked for the password.
In your browser, not on a server
qpdf, compiled to WebAssembly and served by this site, encrypts each PDF with AES-256 using the password you type, the same standard Acrobat uses. The encrypted file is written in your tab and handed to your browser’s download.
Compared with upload-based tools: Uploading a document to protect it hands the unprotected copy to a stranger first. Here the only copy that ever exists outside your device is the encrypted one you choose to send.
Verify it yourself. Give the page a short while after your first run to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
How strong is the protection?
The PDF is encrypted with AES-256, the strongest standard PDF encryption, which Adobe Acrobat, Preview, Chrome, Edge and Firefox all open. The protection is only as strong as the password, so use a long one.
What if I forget the password?
The file cannot be recovered, by us or anyone else: there is no copy of the password anywhere. Keep the unprotected original, or store the password in a password manager.
Why not use an online PDF protector?
Because the reason to add a password is that the file is private, and an online protector has the unprotected file the moment you upload it. Here the encryption happens on your device.
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Guides
- How to password protect a PDFUnlike removing a password, adding real encryption usually needs a dedicated tool rather than a built-in export option. Here is what works.
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