The interview process at 1stdibs was thorough and challenging, but very fair. There were three rounds of interviews.
My first interview was a phone screening with the director of iOS development at 1stdibs. My interviewer asked me about my background, and then we did some fairly simple live coding.
Within a day or two of the first interview, I was invited to a second-round interview at the 1stdibs office. This interview was several hours long, and was divided into three sections, where I met with different members of 1stdibs's iOS team. I met two pairs of developers, and then met the director of iOS development. Each group I met asked me to solve two programming problems. The team did everything they could to make the process as stress-free as possible. I wasn't required to work on a whiteboard. For general programming questions, I was allowed to work on paper, or even verbally explain how I would do something. For iOS specific problems, I was given a computer with Xcode. In fact, my interviewers encouraged me to use Xcode's debugger to help me solve any problems I encountered. Overall, they wanted to see how I solved problems, and encouraged me to ask questions and explain my thinking, rather than expecting a specific "correct" answer.
After my in-office interview, I had a phone interview with Ross Paul, 1stdibs's CTO. He asked me a few brain teasers and talked a bit about 1stdibs.
Overall, my experience interviewing at 1stdibs was very positive. Everyone I met was friendly and respectful of my time. 1stdibs was prompt about getting back to me after each round of interviews, which I greatly appreciated.