● Free · no signup · ~5 min
Try a system design drill
One focused, interview-style prompt. Write a short answer and an AI interviewer grades it in seconds.
The prompt
A payments service writes every transaction synchronously to a single primary SQL DB and latency is spiking at peak. Identify the bottleneck and propose a fix.
Strong consistency is requiredState what you trade away
Your answerFill in each line — schema, bullets, or prose.
Bottleneck ◯·Fix ◯·Trade-off ◯
No diagram needed for a drill — that's what the full interview is for.