Big Tech Interview Questions: What the Rounds Are Actually Measuring
Big tech interviews run a recognisable loop, and the common mistake is preparing for it as one exam: over-preparing the coding round, which is the most studied and least differentiating, and under-preparing the experience round.
Quick answer
Start with the outcome you need
You have a loop coming up at a large technology company and want to know what each round is actually measuring, so your preparation time goes where it changes the outcome.
What to remember
Three rounds measuring three different things
Large technology companies run a recognisable loop, and candidates who prepare for it as a single undifferentiated exam underperform in a specific way: they over-prepare the coding round, which is the most studied and least differentiating, and under-prepare the experience round, which is the least studied and most differentiating.
Coding measures whether you can turn a problem into correct code while talking. System design measures judgment under ambiguity. The experience round measures whether your past work holds up when someone digs. Different preparation, different failure modes.
The coding round is about the narration
Correct code in silence scores worse than slightly slower code with the reasoning exposed. State your assumptions, name the approach and why you rejected the obvious alternative, then write.
Say the complexity before you are asked, and say what dominates. Test with a real edge case rather than announcing that you would test.
If you get stuck, narrate the stuck. What you have tried, what you now suspect, what you would try next. That is recoverable. Silence is not, because the interviewer has nothing to score.
System design rewards scoping, not architecture vocabulary
The prompt is deliberately underspecified. Candidates who start drawing lose to candidates who first establish what is in scope, roughly what scale, and which properties actually matter here.
Do a quantity estimate out loud, even a rough one. Requests per second, storage growth, read to write ratio. It shows the design is grounded and it usually determines the interesting part of the design.
Then take a position and defend it. Naming the trade-off you are accepting and what would make you choose differently is the behaviour being assessed. A design that lists every option without choosing scores poorly.
The experience round is the one people skip
Expect several passes over the same project, each going deeper. The first pass is fine for almost everyone. The third is where the difference shows.
Prepare two projects to real depth: business reason, constraints, rejected options, your specific decisions, measured outcome, what failed, what changed after. Depth beats breadth here — two projects you can defend completely beat six you can summarise.
Expect direct questions about ownership. Answer them precisely. This round is also where conflict and failure questions land, and a real disagreement with a real resolution is a better answer than a smooth one.
Practice checklist
- 01Solve problems out loud, including complexity, before being asked.
- 02Practise being stuck out loud: tried, suspect, would try next.
- 03Open every design answer by scoping and estimating, not drawing.
- 04Take a position on one trade-off and defend it under pushback.
- 05Prepare two projects to a third level of follow-up, not one.
- 06Write down exactly what you owned versus supported in each.
Questions to practice aloud
How did this feature change user behavior?
What did you trade off to ship on time?
How did you protect the system during a traffic spike?
Which metric determined whether the launch succeeded?
Frequently asked questions
Should I grind more algorithm problems or prepare projects?+
Whichever is further behind, but candidates usually misjudge this. Coding is the most practised round and rarely the differentiator at mid and senior level. The experience round is typically the least prepared and the most decisive.
How much system design detail is expected from a mid-level candidate?+
Clear scoping, a reasonable estimate, one defensible decision with its trade-off named, and awareness of the next bottleneck. Depth on every component is not expected; refusing to commit to anything is penalised.
What if my experience is not at large scale?+
Explain the constraints you did have. Small teams, tight deadlines, legacy systems, and limited budgets are real constraints, and reasoning under them is what is being assessed rather than traffic numbers.