I applied online. The process took 1+ week. I interviewed at Jane Street in Aug 2016
Interview
I applied online. A week later I was asked to do a phone interview. The interviewer called me from the NYSE floor. He was friendly. The interview consisted of 3 math questions and then I got to ask him questions about the firm. The interview lasted 25 minutes.
Interview questions [1]
Question 1
I'm thinking of an integer with no 0s or 1s. When you multiply all the digits of the number together, you get 10,000. What is the largest number I could be thinking of? The smallest such number?
They tend to examine the logical thinkers that can communicate clearly and concisely, and some problem-solving exercises intended to explore how you gather and apply new information, very different from other tech companies' interviews.
Initial application and online assessment. Had a first round behavioral interview where they asked me about myself, my experiences, and a couple of brain teasers. The interviewer was very nice.
Phone interviews (at least 3) - questions were of mixed difficulty (some pretty hard) but the interviewers were friendly and they gave helpful hints. Kind of fun - review probability and game-type questions.