Did Plaid's technical screen last month while employed (hence: posting on my lunch break). Here's what the coding interview actually looks like, because I couldn't find a clear answer anywhere.
First technical touch is a 60-minute CodeSignal OA. Two problems. Standard time pressure. The difficulty range I've seen people describe varies a lot but for the senior SWE level I was targeting it was one medium and one medium-leaning-hard. No dynamic programming deep-end stuff, but the medium-hard had a graph component with a twist that you don't immediately see if you pattern-match too fast. Read the problem carefully.
After OA: a 45-minute live coding screen with an engineer. One problem, with follow-ups. The base problem was straightforward (think BST or sliding window level), but the follow-ups pushed toward edge cases and time complexity optimization. They asked me to analyze space complexity explicitly, which some interviewers skip. Don't skip it.
Language: Python and Java most commonly accepted. I did it in Python, no issues.
Difficulty honest take: harder than Stripe's initial screen, similar to a solid LeetCode medium with good test coverage awareness. Not Codeforces hard. Not easy enough to coast on pattern memory. You need to actually think and explain at the same time.
One thing that felt different: the live coding interviewer was clearly reading my thought process, not just waiting for me to produce correct code. I talked through why I was rejecting a naive O(n^2) approach before writing anything and that seemed valued. At a few companies I've interviewed at recently, the interviewer just sits there. Plaid's was engaged and asked clarifying questions mid-solve.
Total time from OA invite to completing the live screen was about 2 weeks. They move at a reasonable pace. No 3-week ghosting between rounds (so far).
I'm now onto the full onsite loop. Will report back.