so i interviewed for McKinsey's junior software developer track as a new grad (class of 2025) and had no idea what i was walking into. want to document this for others in the same boat.
first thing: McKinsey hires engineers into different tracks. there's the consulting-adjacent tech roles where you embed on client projects, and there are the internal product/tech roles. the process differs. mine was for the client-facing track.
what they tested coding: two rounds of coding questions. these felt closer to LeetCode medium than the case-heavy stuff you see in business analyst interviews. arrays, strings, one graph traversal problem. they gave me a choice of language, i used Python. they care about correctness and clean code, not just getting the output. system design (lite): for a new grad they don't expect staff-level design. but they did ask me to design a simple URL shortener and think through trade-offs. focus on explaining your reasoning clearly more than getting every detail right. PEI: this is where new grads get caught. the PEI is the same structure as for experienced folks. they want real stories with real impact. 'i built a feature that reduced page load time by 40%' is better than 'i worked on the frontend team.' if you don't have internship stories with numbers, dig into class projects and be specific. a case: yes, even for new grad SWE roles, there was a light case. it's not a full McKinsey business case, more like 'here's a client problem, how would you analyze it.' i think they're testing structured thinking and communication.
how i prepped leetcode: ~60 mediums over 6 weeks, focused on arrays, graphs, DP basics system design primer (the free github one is enough for new grad level) prepped 3 PEI stories and practiced saying them out loud watched two McKinsey case interview videos just to know the format. didn't do full case prep.
the honest verdict
i didn't get the offer. made it to final round. i think my case was weak and one of my PEI stories lacked specificity. but the process was fair and the interviewers were sharp. if i did it again i'd spend more time on the PEI and less time on leetcode grinding.