TrialPay Software Engineer interview questions

1 phone interview with the recruiter for cultural fit. 1 technical phone screen with an engineer. 1 on-site visit (4 technical interviews, lunch break, and coffee break).

Finished a couple of technical questions before phone interview. A phone interview was arranged then. After the phone interview, it's an onsite 1:1 interview. My 1st interviewer told me "good luck" and told me stop the interview here after an one-hour design question discussion. Although I felt positive on my performance on this design problem, the interviewer rejected to provide feedback about my answer. Pros: HR recruiter is very responsive. Cons: No feedback.