I was introduced to Jon at Duo, who skyped with me to determine whether or not there was a fit on both sides.
This was followed by a Technical Phone Screen with Engineering Managers. This covered a variety of questions ranging from general theory to specifics of the technologies I listed on my resume.
Onsite Interview:
During my onsite I had non-technical interviews with the Director of Engineering and the CEO in the morning, followed by lunch with the CTO. Everyone was very impressive and it is very obvious that Duo is committed to building a high quality team of people to work with.
The afternoon was two technical interviews, each with a different engineering manager. One interview covered front end engineering (JS/HTML/CSS) and the other covered Algorithms/Data Structures. Both were challenging and on par with the companies I've interviewed with in San Francisco.
The day ended with an exit interview and dinner with the team.
The recruiters and schedulers at Duo did a great job of keeping me in the loop and were extraordinarily kind in scheduling my trip over a weekend so I could spend some time with family I have in MI (I mention this because I think it is a microcosm of the great culture they are building there).
Overall the process, the team and the offer were all great. I'd highly recommend Duo Security to anyone looking for a great place to work.