Initial online coding test to screen candidates. 3 questions that were challenging, based around sorting lists, calculating averages. Watch the edge and corner cases, and pay close attention to running time. Was invited to take part in an assessment day (offered an all-in-one interview due to distance travelled, rather than the usual 2 step process). Part 1 - Two technical tests. These are written tests 45 mins each, one using a made up language (like assembly), the other based in Java. Code completion of logic blocks, working out what functions do. Java is based around a linked list implementation that you have to complete. Less than half of the applicants passed that stage and were invited to continue. Part 2 - Talk from Ocado about the company and tour of the warehouse, very interesting, opportunity to ask a lot of questions. Part 3 - Technical Interview. 2 developers asked general Java based questions. Understanding of ArrayList implementation as an example. Then a whiteboard test, they don't seem to use standard challenges, mine was related to string comprehension. That was tough, but I talked through it and got there in the end, which seemed to impress. Part 4 - Manager Interview - One of the team leaders came in for a more general interview, was asked about experience / CV / areas of interest. Worked out where my passions were and strengths and weaknesses. It's a long day if you get an all in one interview, started at 10, I was out at 5:15 though there is a little down time in the middle of the day where I had a chance to talk to the other candidates.