The interview process at Gatsby was really positive, and is described in detail on their website.
There are four steps: 1) 30 min interview with internal recruiter, 2) 1 hr interview with hiring manager, 3) 1 hr interview with technical staff, 4) 4-6 hr paid take home project. A big positive is that Gatsby is really speedy making decisions. I usually received word about my interview progress within a day for each step.
Off the bat the recruiter was friendly and introduced me to the company and asked some behavioral/situational questions about my background. Questions like "Tell me about a time you encountered X." A big plus was that the recruiter didn't ask my salary expectations. Most companies do, but it shows a level of recruiting sophistication to not ask.
The interview with the hiring manager also discussed professional situations and more specifics about my work history and technical ability.
The technical portion of the interview consisted of two software engineers who dug deeper into work history and technical ability. A big plus is that we spoke about real tech stuff. No puzzles, no whiteboards. I got a great feel about the team and rapport between potential future team members during this step.
The final step was the paid take home project. The estimated time to completion was 4-6 hours. I don't want to give away too much about the project, which may be different for different roles, but in my case was a great opportunity to set the tone for what would be the future role.
Interviewing at Gatsby was a very positive experience. I felt like the staff got to know me during the process, and I got to know the company and future team.