Carbon is a relatively new startup company, so the interview process (and probably the internship too) is pretty informal. The recruiter said that the process is first an HR phone screen, then 1-2 rounds of technical phone interviews with a software engineer. The conversation with my recruiter went really well, and he confirmed that it would be followed by an interview with one of the software engineers. However, the recruiter never got back to me about next steps, and even after several follow up emails, I never heard from the recruiter again. This was one of the rudest and oddest experiences I have had with any interview process.