I applied online. I interviewed at Google (New Delhi) in Mar 2018
Interview
First and very important rule, if you want to participate in GSOC, choose some 3-4 organizations from the list of previous participants (Its very probable that they are going to be selected for next year too) and start playing with the tool/application i.e. install, configure, run on local, run for your own test cases etc. The idea is to evaluate your assumed interest for that software and if it turns out to be interesting you would end up being comfortable with it.
After that you need to prepare a proposal and submit it
Application
I interviewed at Google
Interview
home assignment via the google interface. was given two coding questions. didnt seem too tricky but i didnt pass. both solutions were O(n) so i dont know exactly why. i recommend looking up tricks and small things they are looking for to know
Interview questions [1]
Question 1
one code question was to sort numbers in some order and to collect points. a simple scan in O(n) seemed to work
two different zoom interviews, where each asked one leetcode medium or hard question. The interviewers were nice and they tried to guide me in to the right direction to answer the questions
I applied through college or university. I interviewed at Google
Interview
I was asked a few leetcode problems that can be found online searching google leetcode questions. the home test was very easy. I practiced a lot of questions and read the cracking the interview book, was very helpful.
