At Gigas I started being the first software engineer. In six very busy months we had to bootstrap a hosting startup with a few people.
I was leading the software development and development decissions regarding architecture and platform communication, taking care of the licensed software we were using and the new platforms we were creating to achieve our goals in a timely fashion.
Among the most interesting achievements we made when I was there, we developed a one-click load-balancer service, one-click auto-scaling, the billing backend and the integration between the support service and our platforms.
Our applications were using different technologies, mostly Python with Tornado, Django (where we added a billing system within the admin) and other legacy code in PHP.
Apart from the huge technical knowledge on systems and architecture I got from this position I also learnt something more important, handling a serious amount of pressure.