This is not a typical “Founding Engineer” position at an early stage company. In particular, this role will involve more research than similar positions. You should be prepared to spend around half of your time on research and half on engineering.
The ideal candidate has experience in both. However, we don’t strictly require research experience as long as you have a strong quantitative background and an eagerness to learn. We do require proficiency in both web development (Javascript, Node.js (http://node.js)) and Python.
Our work is fundamentally open-ended and requires candidates who are comfortable with the uncertainty that brings. As on any ambitious project, much of your time will be spent on failed experiments. However, you will have a high degree of autonomy and freedom to solve the problems you are confronted with. As such, the ideal candidate enjoys this freedom and the challenge it presents.