I submitted my resume on early of June, 2017 and got the phone interview in 2 two weeks. It is about going through your resume and the questions like "Why Kepler". The next round is to implement a project which is to design APIs. Although there is no requirement for language and package, I suggest to use Python, especially Python3 - cause it is their language.
The following round is in-person interview. Remember the company's address is 6E 32 st, not 6 (W) 32st - it is a hotel : ) The big open office is quiet, it seems everyone is focused on their work. The interview includes live coding (easy level in algorithm), system design (given a Json file, how to optimize the query), debugging (3 simply files, but everyone has problems. You'd better go through the Python build-in functions first, be familiar with exceptions and object constructor function ). And some behavior questions. I am not sure where the problem is, I spent more than 30 min to debug three easy files (only one engineer cares about how I implement) or they don't like my response for the behavior questions, anyhow, I get a refusal letter in one week.