I worked at Twitter part-time starting June 2007. I've never talked much about this in public. I'm revisiting it because of the complete disaster Elon Musk has made of Twitter. His sabotage of the company has felt personal to me. It hurts to watch him destroy something I helped create. The recent API debacle particularly stings.
Early Twitter was chaotic without enough experienced engineers. I acted as a management advisor. I helped the engineers organize and the executives work better with engineering. I did some good but I've always wished I could have done more. In retrospect, I should have committed more time. I did enjoy a long insider relationship with some of the leadership and was of some help that way.
The most useful concrete thing I did was what we called "Nelson's graphs". I made some simple measurements of performance like tweet delivery times. Post a tweet to one account and see when it shows up on another account's timeline. (Note this graph shows an average of 15 minutes!)
Simple but useful. It was a clear view of whether the site was working and ended a lot of arguments. These days we'd call this basic devops but in 2008 it was still a novel idea. My graphs kept running for several years even after they leaked to the press.
I grieve for Twitter now. I grew to love it over the years and was an enthusiastic user. Musk has ruined Twitter both culturally and technically. I suspect Twitter will survive in some new smaller, crueler form. But I've moved on to Mastodon and that's working for me.