Applied through a recruiter. There were lots of rounds but it didn't feel that way because of how short each round was, and how quick Decision Tech were to give feedback!
First round was a quick phone call with the Head of Development. It didn't go into too much depth - just a general chat about my work history and reasons for applying.
Second round was a take-home coding challenge. Vanilla JS based - adding functionality to a made up FE framework.
Third round involved reviewing the take-home challenge with a developer from Decision Tech, and then pair-programming to implement more functionality and unit tests.
Forth round was a chat with the Head of Development (again) and a non-technical manager. This covered some higher-level (architectural) technical concepts, and ways of working.
Fifth and Sixth rounds were apparently a formality. The fifth round involved talking with the CTO, again talking about why I applied at Decision Tech, what I enjoyed about programming, work history etc. Sixth round was a chat with someone from HR. Both of these were quite relaxed.
All things considered I had a very positive experience. Decision Tech was very efficient throughout the process and left a very positive impression on me. I was offered a role, but the only reason I declined was because I had an offer elsewhere that was more suited to my personal situation. It was a difficult choice to make!