There were about 9 calls/interviews from start to finish, starting with a recruiter, then moving to a technical discussion, followed by two technical interviews (one system design, one coding), then a final on site consisting of four additional 30 minute interviews, followed up by a final offer call. During each step of the interview process you won't be blind sided by anything unexpected, they give you more than enough context and information to be successful at each stage of the pipeline.