I applied to Zeiss twice. First one I was rejected due to my nationality. In the second one I went through 3 interviews including a presentation in person for which they offered to pay expenses but never did. They never came back to me with a formal rejection, they simply stopped replying to my emails. Worst HR department and worst company you could ever apply for.

The first round was an online screening, followed by an on-site interview, which went well. The interviewers were professional, and one round involved a case study where I was asked to provide my views on a business scenario.