1PDF

Lock PDF

Security

Set an opening password and optional owner permissions for your PDF.

Drop your PDFs here

PDF files · up to 50 MB each

Choose a PDF to begin.

Processed on your device. Files and passwords are never uploaded. Your new copy uses AES-256 encryption.

How to lock your PDF

  1. Choose an unlocked PDF.
  2. Enter a password and confirm it.
  3. Lock and download your protected copy. Keep the password so you can open it.

The new copy keeps the document’s pages, text, forms and links.Existing digital signatures become invalid when a PDF is rewritten. Your original file stays unchanged.