OA included 4 questions on CodeSignal, with the first two questions being very easy and the last two being quite tough. Didn't score the highest, but received a followup "power day" interview, consisting of case study and system architecture.
Design a mock banking web app
The following metrics were computed from 400 interview experiences for the Capital One Software Engineer role.
Capital One's interview process for their Software Engineer roles is fairly selective, failing a large portion of engineers who go through it.
Candidates reported having very good feelings for Capital One's Software Engineer interview process.