wrapped up mercury's frontend engineering loop two weeks ago. senior-level, remote-first role. sharing because most interview prep advice for frontend roles is way too generic.
the recruiter was upfront: mercury is a fintech product with very high standards for UI quality and correctness. if something breaks in a dashboard, it could mean a real customer sees wrong financial data. that framing stuck with me through the whole loop.
technical screen (60 min): started with a vanilla JS question, no framework. they wanted to see how i think about the DOM and event propagation without relying on React abstractions. not a gotcha, but if you've been in React land for years and haven't thought about fundamentals, brush up. then we built a small component together: a data table with sorting and pagination. more about communication and design choices than raw speed.
onsite (virtual, 4 rounds):
performance and architecture round. we talked about rendering strategies, how to handle large datasets in the browser without killing performance. virtualization, debouncing, memoization tradeoffs. i got the sense they deal with real table-heavy UIs given the dashboard nature of their product.
state management deep dive. they weren't dogmatic about redux vs. zustand vs. context. they wanted to hear my mental model for when local state is enough and when you lift it. i talked through a real example from a previous job where we over-engineered state early and paid for it.
access and reliability round. surprised me. a whole round on accessibility (aria attributes, keyboard navigation, screen reader testing) and also on how you build UIs that degrade gracefully when an API is slow or returns an error. fintech context makes that matter more than at most product companies.
behavioral. standard but specific. "tell me about a time you caught a frontend bug that had downstream financial impact" is a real question they asked.
the offer i got: around 210-230k TC for a senior role, remote. that's in line with what i've seen for similar stage companies. not FAANG but not bad.
overall mercury feels like a place that actually thinks about craft. it wasn't a leet-code gauntlet.