Don’t blank when they slide the drawing across.

I built this because I needed it and couldn’t find it. I’m a mechanical engineer with a master’s from Arizona State, and I spent my career in manufacturing plants on the consumer appliance side — ranges, cooktops, brackets, tolerances, line trials. Then I went after a data center engineering role. Chillers, cooling towers, power chains, controls, mission-critical infrastructure. On paper, almost none of it overlapped with what I did every day.

So I scrambled. 14 browser tabs, PDFs from a decade ago, YouTube videos that spent 9 minutes explaining what a bolt is, and AI that would confidently invent questions all night without ever knowing what a real loop actually asks. There was no single place I could trust. Not one built for engineers like us.

I prepared at night, after full days at the plant. I had to learn entire subjects from scratch — not just the answers, but the concepts underneath them, so they’d hold up when someone asked “why” three times in a row. Things I hadn’t touched in years. Things I had never touched at all. I did it in the hours after work because that was the only time there was.

It worked. I made the jump, into a field that had nothing to do with where I came from. But it was far harder than it needed to be, and almost none of that difficulty was the engineering. It was the preparation nobody had organized.

So this is that place, built for the people coming behind me. Every question has a model answer, a plain-English explanation underneath so it actually teaches, and the reason interviewers ask it. Concepts first, because that’s what survives a follow-up question.

I’m not going to promise you a job. Nobody honest can, and anyone who does is selling you something else. Here is what I will promise: your preparation will be organized instead of frantic, you will understand what you’re saying instead of reciting it, and you will walk into that room with your confidence intact. That’s the part I can actually give you — and it’s the part that was missing when I needed it.

— a mechanical engineer, MS from Arizona State, who made the jump and remembers exactly how it felt

You’ve seen the posts: “500 problems solved.” That works for algorithm interviews, where volume drills pattern recognition. It is the wrong way to prepare for ours. A hardware loop doesn’t ask you to recognize a puzzle type — it hands you a drawing, asks why, then asks why again, and a thousand memorized answers collapse at the second why.

So you won’t find a solved-counter to show off here, and the bank will never be padded to hit an impressive number. Every question earns its place by teaching a concept that survives follow-up questions — with a model answer, a plain-English explanation so it actually sticks, and the tactical read on why interviewers ask it. Thirty questions understood cold beat three hundred skimmed. Your tracker measures what you’ve made yours, not what you’ve scrolled past.