LastPass is a very convenient tool for managing and autofilling usernames and passwords on internet sites. How does LastPass determine which inputs to autofill? My research and testing showed that LastPass as of 2/18/2019 uses the following rules.

  1. There must be at least one <input type="password" /> on the screen.
  2. If you have at least one password input then all the other text inputs will get the LastPass grey ellipses box.
  3. You can programmatically tell LastPass to ignore a field with data-lpignore="true" on the element.
  4. Input fields with ids or names containing email, password, or user are candidates for LastPass to autofill.
  5. Having a single extra text input seems to confuse LastPass and no grey ellipses boxes show up.