I applied through an employee referral. I interviewed at Mixpanel
Interview
Visited office (I knew a current employee) and asked them lots of questions, decided I liked them. Onsite spanned two days, but both days were fairly short (3ish hours). I was asked lots of questions about stuff I had built and listed on my CV, one whiteboard problem (easy) and one coding problem (medium difficulty), and lots of talking through what I would build in detail. I felt like they did a good job getting to know me, and gave me plenty of opportunity to more learn about them. It typically took 1-2 days to hear back and move to the next phase.
Interview questions [1]
Question 1
nothing really unexpected. it was a pretty reasonable eng interview.
I applied online. The process took 3 weeks. I interviewed at Mixpanel (San Francisco, CA) in Apr 2016
Interview
First I was asked to complete a timed online challenge. There're roughly 50 questions covering various coding languages and software engineer knowledge. I quickly realized that no one could answer all the questions correctly so I just relaxed and did my best.
One week later they told me that they'll continue on to the phone interview. Soon after that I attended the afternoon onsite interview. Note during onsite they're actually using the same collaborate website as phone interview, meaning you'll be coding on an (old) Macbook instead of whiteboard.
I didn't get an offer in the end, but the people I met are very nice and they helped accelerate the process due to my schedule.
Interview questions [1]
Question 1
They're looking for almost full stack engineer with focus on machine learning, and they emphasize on communication and presentation skills.