Most successful project? - well its hard to define success?

Get paid a wage in my day-job to work on other peoples software that I know are still being used but it doesn't matter since I got paid - success!

Made a web-app for a gaming community that gets about 150 users each day. Well I don't get paid but I do use the app myself and I learned while making it - more successful?

Forked some gaming community web app that did not support the latest game updates. Updated it and hosted on github pages. It gets about 1k users per day. Quite popular but since someone else wrote most of the code I feel it shouldn't count?

Maybe one day I will make something that people use and it also makes money for me somehow.. but I hate advertising and I rarely pay for apps/software so I'm not sure if its possible?