I was first contacted with someone from HR. The questions asked here are to gauge your interest in the company and see if your skills match what they are looking for. After that went through, I was scheduled for a phone screen. The phone screen was very casual and the interviewer seemed almost unprepared as he was almost unsure of what to ask. After the first phone screen, I was contacted to do one more phone screen. This person seemed much better than the first, but the style of the interview was very casual and conversational as well. Finally, I was scheduled for a 4 person onsite interview. Something that Twilio has to work on is their reimbursement policy - it's terrible. They only provide you with $600 (yes, you have to book your flight and hotel yourself) and they don't reimburse you for food. Take note that for someone flying into San Francisco, a flight is at least $300 and good luck finding a hotel for less than $150 a night. That threw me off a little bit, but whatever, it's a start-up. Their offices are really quite small for the amount of employees that they have and the place seemed really crowded (it's all one big open space). They do, however, have a pantry and fridge full of food and they bring in lunches and dinners throughout the week. The onsite interview consisted of 4 interviews and the questions that were asked were mostly pertinent to the languages I am mostly comfortable with, but they seem to like Ruby quite a lot. They also asked a lot of questions on past projects and if I have used Twilio for my own projects. This is probably pretty important to them. I would recommend studying on networking, coding, and distributed computing problems.