* Transmission. I learned to write my own proxies, relays, web servers, raw http client/server, websocket server/client, and more. This has been super helpful f

* Transmission. I learned to write my own proxies, relays, web servers, raw http client/server, websocket server/client, and more. This has been super helpful for personal projects. * Test automation. I once wrote this test automation tool executed tests in the browser, file system, and command line. It also allowed remote execution of tests on other machines running the same application. That was super helpful and was the best window into performance analysis.