My friend, who currently works at Sift, spoke highly of the company and referred me for the position. The interview process started with a phone screen with a manager on the engineering team, where I described my background and a project I worked on. It was then followed with an on-site that was a combination of several technical slots, chats with the hiring manager and head of engineering, as well as lunch. They asked for references after determining there's a good match.
The entire process was great. The recruiter was very prompt in answering questions, and she gave a nice on-site preparation that described each slot and what to brush up on for those slots. The engineers and managers and PM I spoke with were smart and easy-going. Culture fit and collaboration seem to be things they highly value. They were also very open about sharing the company's plan while I was evaluating the offer. That's something I always ask about when considering any pre-IPO/startup company. They even asked if it were okay to send me a thank you card, which turned out to be a hand delivery by an actual human! That was a surprising personal touch.
There's nice tech there too. ML is what the company was founded on, but there's also lots of data that an application engineer will build scalable features to extract value out of. I ultimately declined the offer because personally, I wanted to pursue a non-technical opportunity.