Password Protect PDF
Add an opening password to one PDF locally — no upload or account needed.
- Runs in your browser — files never leave your device
- No sign-up, no limits
Drop a PDF here, or click to choose
One PDF up to 100 MB · encrypted only on this device
Creates an AES-256 password required to open the downloaded copy.
Your PDF and password stay in this browser tab. Nothing is uploaded or saved after the protected copy downloads.
How to use
- Drop in a PDF or choose one from your device.
- Enter the password people must use to open the downloaded copy, then enter it again exactly.
- Select “Protect and download.”
- Share the password separately from the _protected.pdf file.
This sets a password to open the PDF
The downloaded copy asks for the password before a compatible PDF reader displays its contents. This tool uses qpdf WebAssembly to create AES-256 encryption, the encryption choice qpdf recommends instead of legacy 40-bit or non-AES 128-bit protection. It does not add “do not print” or “do not copy” controls: reader-enforced permission restrictions are not reliable content protection, while an opening password encrypts the document itself.
Your document and password do not leave this browser tab
Adobe’s online tool says files are handled by Adobe servers. iLovePDF shows upload speed and a “Protecting PDF…” server-processing stage; Smallpdf’s Korean page says uploaded files are deleted after 1 hour. Here, the selected PDF and the password are sent only to a Web Worker in this browser. They are never uploaded to Betterbit, the password fields are cleared after download, and neither value is stored in browser storage.
AES-256 compatibility and the 100 MB limit
AES-256 PDF encryption requires a reader that supports PDF 1.7 with extension level 8 or newer PDF encryption. Current Acrobat and modern browser or desktop PDF readers are usually suitable; very old readers may not open the protected copy. One PDF up to 100 MB is accepted because browser processing holds both the source and encrypted result in device memory. The visible stages continue in a Web Worker if you switch tabs, and Cancel stops that worker without discarding the original. Keep the original: creating a protected copy changes the file and can invalidate an existing digital signature.
Frequently asked questions
Are my PDF and password uploaded?
No. This tool encrypts the selected PDF in a Web Worker inside your browser tab. No PDF bytes or password are sent to a Betterbit server, and the password is not saved in browser storage.
What encryption does this password-protect PDF tool use?
The downloaded copy uses AES-256 PDF encryption and asks for the password before its contents are displayed. AES-256 encrypted PDFs require a reader that supports PDF 1.7 extension level 8 or a newer compatible PDF encryption format.
Can I stop someone from printing or copying a protected PDF?
This tool protects opening the document with a password; it does not add printing or copying restrictions. PDF readers do not consistently enforce those restrictions, so they should not be treated as a way to prevent recipients from copying content they can view.
What happens if I forget the password?
The password is required to open the encrypted copy and is not stored by this tool, so keep it in a password manager or another secure place. Keep the unprotected original in a secure location if you may need to create a new protected copy later.
Can I protect a PDF that already has a password?
This tool accepts an unprotected PDF. If the file already asks for a password, first use the PDF password removal tool with the current password, then protect the resulting copy with the new password.
Is there a PDF file size limit?
Yes. This tool accepts one PDF up to 100 MB so the browser can safely keep both the source and encrypted output in memory. There is no account requirement or daily usage limit.
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Updated 2026-10-24