Password protect a PDF without uploading it
Add real AES encryption to contracts, invoices, and tax returns, right in your browser. Pick 128-bit or 256-bit, set the password, download the protected file. Nothing is sent to a server.
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Set Password
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Encrypt a PDF without Adobe Acrobat
PDF's password protection is real encryption, and you don't need a paid Acrobat subscription to apply it. PDFSmith adds AES encryption to your file inside the browser tab. No upload, no account, no watermark.
Documents worth locking
Anything you'd hesitate to leave on a printer: signed contracts, offer letters, invoices with bank details, tax returns, medical reports, ID scans. Email has no real protection of its own, so the password on the attachment is what stands between your document and whoever happens to intercept or misdirect it.
How to password protect a PDF
- Drop your PDF into the tool above.
- Choose AES-256 (recommended) or AES-128 and type your password.
- Download the protected file. Every reader will now ask for that password before opening it.
Picking a password people can't guess
Length beats symbol soup. Four random words ("copper lantern drift quiet") are easier to say over the phone and harder to crack than "P@ssw0rd!". Whatever you pick, don't reuse a password from another account, and send it to the recipient over a different channel than the file itself: if the PDF travels by email, the password goes by text message.
Good to know
- AES-256 is the same standard approved for top-secret government documents. AES-128 is still strong; use it only for compatibility with very old readers.
- The same password is set as both the open password and the permissions password, so recipients get one simple prompt.
- No recovery exists. If the password is lost, the file stays locked. That's the point.
- Free and unlimited: no sign-up, no watermarks, no daily cap.
Already have a locked file whose password needs updating? Change the PDF password here, or read our guide on protecting PDFs without Adobe Acrobat.
Frequently asked questions
Which encryption does PDFSmith use?
AES with a 128-bit or 256-bit key, the same standard used by banks and governments. We recommend 256-bit for anything sensitive.
Can I password protect a PDF without Adobe Acrobat?
Yes. Acrobat's security features sit behind a paid subscription. PDFSmith applies the same AES encryption from your browser tab at no cost, and the file never leaves your device on the way in or out.
What happens if I forget the password I set?
There is no recovery. PDF encryption has no back door by design, so store the password in your password manager before you close the tab.
Will the recipient need special software to open it?
No. Every mainstream reader (Acrobat Reader, Preview, Chrome, Edge) asks for the password when the file opens. No plug-ins required.
Does it work on my phone?
Yes. The tool runs in any modern mobile browser, so you can lock a document right before emailing it from the same device.
Try it with one of your own files
No account needed. Pick a tool below and your document stays in the browser tab from start to finish.
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