Lori by Joe Herbert

Simply select the questionable character or text, right click, and a message will appear in the top left of the screen clearly showing whether the character is an L, an I or a 1. The message will automatically disappear after 5 seconds leaving no trace. This is a very minimal add-on which does nothing except create a small box when required, and as such should have very little impact on performance and provides no security risk. Note: This won't work on the Firefox Addons page, try it elsewhere.