The interview process consists of one first interview with TA followed by a code challenge, a tech interview and then a final interview with the company's CTO. Overall the interview process is simple with only 4 steps, the coding challenge is a simple problem that allows for many different solutions.

I have applied for Senior Java Engineer position from abroad. The first stage was with an HR staff. The interview was easy and the staff asked some general questions about my experience. After a weak the staff sent me an code challenge, and I should solve it in 2 days. The challenge was very tricky, and honestly I enjoyed to solve the challenge. It was two Rest services and asked I solve the problem in O(1) time complexity. I did it well and my algorithms and solutions were complete, I am sure about it. After more than a week, they had not told me any feedback, and then I emailed to the HR staff and asked a feedback about my solutions. The staff apologized about the delay and said by the end of the second week thy will tell me the result. After the week, the staff sent an email and wanted to call me via Skype at the same day of the email ( wanted to call two hours later !!!), I didn't see the email, and I was offline in Skype when the staff was calling, finally I saw the email after 3 hours and said to the staff to setting another time for a call. Surprisingly, she called me one hour later without any prior informing about the time of the call, and incidentally, I was offline again. After 2 days I asked her to set an exact time when I should be available on Skype, surprisingly she told me "No longer need to call you, your challenge feedback was failed !!!!! ". I do not know how it is possible, if my result was failed, you could tell me simply via the first email ! Why did you try call me 2 times !!!! She had written some reasons about this decision, which all of them were wrong. Fore instance, she had written : "-Not constant time or memory" : I tested it again, definitely it runs in O(1) ! "-Returned always 200 with string 201/204 in the bod" : I tested it again, it never return 200 ! I do not know how she had saw these wrong results !!!!! I am sure about my solutions, it seems because I couldn't answer her without prior notice calls, she denied me. I have sent another email and explain my solutions, but I have never got any response !!! I have thought a German company should have more professional manner.