How to lock / unlock
- Add your file. Click the drop zone or drag a PDF onto the page — encryption is detected automatically.
- Choose Lock or Unlock. Locking asks for a new password; unlocking asks for the current one.
- Apply. Encryption or decryption happens directly in your browser.
- Download. The protected or unprotected file downloads straight to your device.
Why do this locally instead of online?
Encrypting a sensitive document by first uploading it to a service is a contradiction — you're exposing the content you're trying to protect during the very act of protecting it. This tool applies the PDF Standard Security Handler directly in your browser's JavaScript engine, so the unencrypted version never travels anywhere.
Frequently asked questions
What encryption does this use?
The PDF Standard Security Handler (RC4, 128-bit key) — supported by essentially every PDF reader.
Can I unlock a PDF I don't know the password for?
No. You must know the current password — this tool cannot bypass or crack an unknown password.
Does the locked PDF work in all PDF readers?
Yes — this encryption method is part of the core PDF specification.
Is the password ever transmitted anywhere?
No — it's used locally, in your browser, only to encrypt or decrypt the file.