At first, as normal, I had an interview with the CEO, their engineers to know about each other. They are interested in me, so they sent me a technical test to do during 3 days. I spent my whole weekends to do it. Sent it to them. Then it's been 1 month there is no feedback. Not even an auto generated consolodation email. A thank you for taking time to do the test would be a minimum polite and professional gesture. I know you are a start up. But I've been through interviews with start up at their hatching state (group of students who did not have any budget yet), and all of them were very professional.