Sometime around 2010 I made a custom skin for an email notification app called Pop Peeper, it's a recording of my pet duck Carl that was downloaded over 11,000 times: https://www.esumsoft.com/pop-peeper/notifier-skins/#Carl

Just kidding. I was lead engineer on a login page for an Experian identity monitoring remediation product for a major data breach affecting over 20M government employees. Millions of people interacted with my code, kinda cool but everything about that code was very boring.