Add Password to PDF

Protect a PDF with a password so it can't be opened without it. 128-bit encryption, runs entirely in your browser.

Password-protect your PDF

Upload a PDF, choose a password, and download the protected file.

Drag & drop a PDF file here, or click to browse
Choose one PDF to protect. It must not already be password-protected.

    Protected file ready

    Password-protected PDF
    0 pages
    Your file and password are processed locally in this browser tab using JavaScript (pdf-lib). Nothing is ever uploaded to Calcooo or any server.

    How to use this tool

    1. Drag and drop your PDF file into the box above, or click to browse and select it.
    2. Type a password and confirm it.
    3. Press Add password to encrypt the file.
    4. Click Download protected.pdf to save the result — you'll need the password to open it.

    FAQ

    Frequently asked questions

    Is my PDF uploaded anywhere?

    No. The password is applied entirely inside your browser using JavaScript. Your file is never uploaded to a server.

    What encryption does this use?

    The PDF standard security handler, Revision 3, with a 128-bit key — the same "Acrobat 5 and later" compatible encryption most PDF tools offer. It's supported by virtually every PDF reader.

    What happens if I forget the password?

    There is no recovery. Nobody — including Calcooo — can remove a forgotten password. Keep it somewhere safe.

    Can I remove the password later?

    Yes, using the Remove PDF Password tool, as long as you still have the password.