I applied for the job online and went through the full interview process. There was a phone screen, online coding problem, and in-person interview.
Overall the interview process was lean and what I expected from a start-up. The online algorithm had two parts, both of which were pretty straightforward. The in-person portion included implementing a backend feature using a 3rd-party library and building out a UI component in React.
I felt like the easier parts of the interview were to make sure I could actually code. The first algorithm was easy and anyone should be able to come up with a solution. The second one required some thought but was in no way hard. I think they were gauging how I came up with solutions.
The in-person one was a little bit harder. I didn't know what the question was but when I got there I was asked to implement a feature using a library I had never used before. The interviewer was there to answer questions. I'm pretty sure they were testing to see how i picked up new things and learned on the fly which is important while working at a start-up.
Then it was a reference check and an offer. Pretty quick, interviewer was responsive when it came to communication via email.