Flow Traders Senior Software Developer interview questions

I was given a link to hackerrank question. It was not too difficult. It had some stages with a couple of different question types. It covered multiple topics. It was easy enough. Then I don't remember

Encountered some red flags during the interview process. HR communicates with slow delays stretched over days and even weeks. After 15 years of C++ experience, they skipped straight to "prove you can code" with a HackerRank test that would make quantum physicists sweat. No call, no feedback, just digital tumbleweeds. Pro tip: If you're collecting resumes like Pokemon cards rather than hiring, maybe mention that in the job description? Turns out I wasn't a candidate - I was market research with a pulse.