Meetup moves tremendously fast when they feel a candidate is a good fit with their culture, and share the same vision of what Meetup is / can become. The first interview is a one on one with someone on your (potential) team. If they want to proceed, Meetup will bring you back for a full day interview (5 1-hour interviews with various team members and a group lunch). A few days later I had an offer and happily accepted.

Two rounds of interview with 2-3 people each time. Standard whiteboard technical interview and behavioral questions. Data structure, algorithms, system design, and front end coding. They look for not just technical skills but also a good culture fit and good attitude, as well as passion for what you do. Standard tech interview prep should cover you on the technical side.

The process leading up to in-person interviews was pretty standard: call with HR followed by tech interviews online. When I came into the office, my opinion of the company rapidly changed. After picking me up late from the front, the HR rep talked to me for a little while. I then had standard whiteboard coding interviews straight from Leetcode (finding palindromes, 2D array sums, etc.). They clearly prefer people who study and memorize questions over those who have the intuition to solve original problems. This was really shown in a question where I quickly solved the actually problem, but was then asked to implement a heap I used from scratch. Again, they clearly prefer those who can memorize fundamentals, and not those who can perform on top of abstractions that were, well... abstracted specifically to solve more complex problems. The interviews also included a lunch, but because the company provides so few perks, the engineers fought over who would get to go with me. The office was mediocre and everyone used pretty dated computers. What really turned me off was how badly many of the engineers lacked any semblance of social skills. Conversation was forced, and by lunch, I had no desire to even finish the rest of the interviews. I pushed through it, until the end of the day, when they forgot about me and left me alone in the room for 45 minutes. After not hearing back for two weeks, I let them know that I had accepted another offer. Then, 4 weeks after that, I received an email thanking me for my time and saying that they were moving on with other candidates. Not a good look - just further shows how lacking they are in terms of culture and social abilities.