How do you want to work today?
Apart from the mock and the untimed blank page, nothing here takes more than fifteen minutes. A short daily session beats an occasional long one.
Daily Rep
One problem, stages 1 and 2 only — requirements and lifecycle. Never a full design. Small and daily beats long and rare. Requirements is also the stage people rush past, which is why it gets its own practice.
Timed Mock
All five stages with phase timers, a follow-up question at the end, and nothing revealed until you finish. Then a report card. It is the only timed mode longer than fifteen minutes.
Follow-up Blitz
Rapid-fire defence drills. Ninety seconds each, then weak answer, strong answer, and the trap. This is the mode that moves the Defence axis, which is easy to neglect when you practise alone.
Concept Check
Concepts resurface on a schedule based on how you rated yourself. It asks for the cost, never the definition, because the cost is what interviewers press on.
Blank Page
An empty canvas with the five-stage scaffold and nothing else. No nudges, no model answer, no checklist. For the last week before an interview, when you need to know you can produce it from nothing.
The five stages, in case you want them cold
- 1Requirements. State assumptions, ask one or two questions that change a box, propose the scope yourself.
- 2Actors and lifecycle. Who touches it (including the system itself), then the main thing's life as a chain of states, with the failure branches.
- 3Numbers. Requests per second, storage, bandwidth. Then: "so the hard part here is ___."
- 4High-level design. Boxes and arrows, every box justified by a requirement or a number.
- 5Deep dive and tradeoffs. The two hardest parts, and after every decision, what it costs.