The Generic HLD Playbook

This prompt only looks like it is about URL shorteners. It stands in for a whole family of questions that share almost nothing in domain and everything in shape: a rate limiter, an autocomplete service, a notification system, a photo store. Intuit reaches for these far more than it reaches for anything about taxes or accounting. They are clean tests of whether you can turn a vague ask into a defensible architecture. So what to carry out of this lesson is the method that produces a strong answer for any of them. Here it runs once, in full, on a problem concrete enough to hold.

The Intuit angle

Most of Intuit's system design rounds are generic HLD, and the design round that decides your offer is the Craft Demo. So a whiteboard prompt like this is graded less on the architecture and more on the lens you bring to it. Candidates report the modal prompt is a shortener, a rate limiter, an autocomplete, a leaderboard, or a small e-commerce or booking flow, not a themed TurboTax or QuickBooks design. What makes an answer read as Intuit rather than generic is what you surface without being asked: a precise DB schema and API contract, and correctness under retries and concurrency. It also means security on a system that touches other people's data, and a sober take on where AI helps. Treat the shortener below as the vehicle, and the reusable method plus that lens as the cargo.