Design rate limiting and quotas for an API with free, pro, and enterprise tiers.
Rate limits protect your servers; quotas protect your business model, and most candidates design one and think they've designed both. The strong answer also covers the part customers actually feel: what hitting the limit looks like.
Updated Aug 2026 · Grounded in real Forward Deployed Engineer interview loops and written to a senior-engineer editorial bar.
Rate limits protect your servers; quotas protect your business model, and most candidates design one and think they've designed both. The strong answer also covers the part customers actually feel: what hitting the limit looks like.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
