Password-protect a PDF
Add an open password to your PDF to restrict access. 100% local processing in your browser — your file and your password never leave your device.
About the encryption level: the engine used here applies standard PDF encryption based on 40-bit RC4 (the same engine as the "Password-protect a PDF" tool), not AES-256 encryption. AES-256 would require an additional cryptographic library not yet integrated into this client-side tool. This protection is effective against accidental opening in a standard PDF reader, but it shouldn't be considered professional-grade encryption for highly sensitive data.
How it works
The password you enter is used to encrypt the PDF's content using the encryption standard built into the PDF format itself: without this password, a PDF reader refuses to display the document's content. The password strength analysis (length, character variety, estimated entropy) is shown live as you type, to help you choose a password that's hard to guess.
Why doesn't it offer AES-256 directly?
AES-256 requires a dedicated, heavier cryptographic implementation that isn't yet bundled in the WebAssembly engine this tool uses. Rather than claim a level of security that isn't guaranteed, we'd rather say so clearly: the current encryption protects against unauthorized opening in everyday use, but it shouldn't replace a real digital vault for highly sensitive data.
If I forget the password, can I recover it?
No, there is no way to recover it from this tool: keep the password you chose somewhere safe (ideally in a password manager), because an encrypted PDF without its password becomes permanently unreadable.
100% local processing: encryption happens entirely in your browser via WebAssembly — your file and your password are never sent to a server.