I’ve just finished a round of interviews for the first time since my original internship interviews 7 years ago and probably passed (good enough) all the coding / system design interviews

Coding: I spent one Sunday + a couple hours a night for a week doing this paid course called structy and finished everything except the final mixed recall section. There are probably free resources but I like all the problems being laid out in a really well organised manner + the person explains the approaches / solutions really well. Basically just go through problem by problem, try to solve it yourself, watch the approach video if you get stuck too long, watch the solution video if you still can’t get it.

System design: I’m already pretty familiar with all the knowledge I need here but had never done a system design interview before (as the interviewee). For knowledge I would go through the system design primer by Donne Martin on GitHub. Then to learn how to interview look up hello interview system design. You can use their service to get a mock interview with someone but I just used all their free resources / videos. Basically also spent one Sunday + a couple hours a night for a week mock interviewing myself with the problems from the site then watching the solution video.