Lifer Highlighter is a free Chrome add-on developed by j-applese3d. It falls under the category of Browsers and specifically the subcategory of Add-ons & Tools. This add-on is designed to enhance the birdwatching experience on eBird's website by highlighting lifers and suppressing ones you've already seen.

With Lifer Highlighter, you can input your life list in the options textarea, which can be easily downloaded from "My eBird". Once you've done that, whenever you load pages on eBird, the birds you have seen before will be displayed in a muted gray color instead of the usual blue. This makes it much easier to identify the birds you haven't seen before.

The add-on provides a basic functionality and allows you to customize the highlight colors according to your preference. While Lifer Highlighter may not offer advanced features, it serves its purpose for birdwatchers who want a simple tool to help them identify new bird species on eBird's website.