The interview was fairly standard, although the use of LeetCode-style questions has largely fallen out of favour in favour of more realistic scenarios. I was therefore surprised that this was used as part of the technical interview.

The main stumbling block for me was the enforcement of HackerRank as the interface for the interview. The lack of a debugger, test suite, whiteboard, scratchpad, and IntelliSense meant that I was restricted to essentially using Notepad to write a solution. This majorly disadvantages people who are visual thinkers and need a tool to represent problems using diagrams.

This use of HackerRank applied to both the coding test and the system design test, which was fairly surprising. Typically, a whiteboard is seen as an essential tool for system design.

Overall, my experience was positive, but the choice of tools severely limited my ability to communicate and plan my problem-solving approach. A suggestion to the recruitment team would be to ditch HackerRank in favour of something that represents a more realistic development environment, or at least allow the use of a whiteboard.

Another suggestion would be to avoid asking questions around US-specific services or products. A good deal of the system design time was spent trying to understand how the product worked and trying to reconcile US finance regulations versus UK finance regulations, rather than actually designing anything. UK regulations are much stricter than US, particularly around custody of client assets, hence the need for a more complex system.

Design a data model for a finance system.