Protect PDF
Set a user password required to open the PDF.
Protect PDF encrypts a PDF with a password using AES, on your device — the password is asked for each run and is never stored. A forgotten password is not recoverable by design.
Protect PDF encrypts your document with a password so it cannot be opened without it. You can also set whether printing and copying text are allowed. Protect PDF is one of UnboundPDF's 53 free browser-based PDF and image tools: it runs on your own device with no upload, no account and no watermark, and reports what it measured on the output.
How to protect PDF — steps & common uses
What people use Protect PDF for
Anyone locking a PDF before sharing — requiring a password to open a confidential contract, statement, or record.
- Password-protect a contract
- Lock a financial statement
- Secure a confidential report
- Require a password to open
- Protect a document before emailing
How to protect PDF
- Add your PDF; encryption is performed on your device with no upload.
- Enter and confirm a password, and choose whether to allow printing and copying.
- Click Encrypt PDF, which then self-checks that the file is truly locked.
- Preview the content and download the genuinely encrypted PDF.
Questions about Protect PDF 6
Are my files uploaded to a server?
No. UnboundPDF processes PDFs locally in the browser — documents are not uploaded to a server. We have no backend that receives, stores, or scans your files.
How strong is the protection?
The PDF is encrypted with AES, and the tool runs a self-check to confirm the output will not open without the password before handing it to you.
What happens if I forget the password?
It cannot be recovered. The encryption is real, so store the password somewhere safe; without it, the file cannot be opened.
Why can I still preview the document after encrypting?
The preview shows your original content for reference, but the file that downloads is the encrypted version that asks for the password when opened.
What encryption is used?
The file is encrypted with AES, so it genuinely requires the password to open — it is not just a display setting.
Can I still open it in normal PDF readers?
Yes. Any standard reader will prompt for the password and open the file once it is entered correctly.
Read more
How your files are handled
The work runs on your own device, inside the browser tab — so there is no server to send your document to.
- Nothing is uploaded. We have no backend that receives or stores documents, so we cannot see your files during processing or after.
- Your device does the work. Large documents are handled in stages, pages are rendered as you reach them, and each job is checked against your device before it starts — so a long run takes longer on a phone than on a laptop, nothing is queued behind other people's jobs, and you can stop a run at any point without touching your original file.
- No account and no watermark. The output is a clean file you can use anywhere, with no sign-up and no hourly cap.
More security tools
Other free PDF utilities that work the same way — in your browser, no sign-up.