There was 1 OA, 1 Technical, and 1 managerial Round.
OA: There were 3 coding questions. The level was easy to medium (Around 1200-1400 on codeforces). I was able to solve them in 28 mins. I got shortlisted for the interviews the next day.
The technical interview was of 40 mins. I was asked a standard question of the minimum number of rooms required to conduct all meetings. The interviewer asked me to code it using OOPS. The good thing about Atlassian interview is that you are allowed to use Google (of course, you can't Google the question) and also you can use the IDE of your choice. The interviewer was very chill and very friendly. I completed the OOPS implementation and testing on my sample cases in 20 mins. After that, I was asked to create a new function for the maximum number of meetings possible in one room. I completed that function in 10 min with proper explanation.
The managerial round started with my introduction. Then he asked me about my project and told me to show it. I shared my screen since I didn't have my site hosted (having a hosted link is more preferred). There was a 15-20 minute discussion about my project. After that, he asked some managerial questions and was observing my behavior whether it aligned with the 5 Atlassian core values. Overall the managerial round was 45-50 minutes.
That evening I was happy to get an internship at Atlassian :)
