Mock system design interview at Microsoft
A live 45-minute round on one of the questions reported in Microsoft interviews, run by an AI interviewer that asks one thing at a time, probes what you say, and weighs what that round is reported to weigh. It ends with a debrief: a score, what was strong, what was missing.
Design a URL Shortener
bit.ly at scale: turn long URLs into short codes, redirect in milliseconds from anywhere, count the clicks.
You will not see the requirements, the numbers or the diagram before you start — that is the point.
What the Microsoft round is reported to look like
45–60 minutes, usually one design plus follow-ups, with the level of abstraction set by the role.
What it weighs
- Requirements and scoping before design
- Reliability, versioning and backwards compatibility
- Concrete component choices with reasons
- Communication: a design someone else could implement from your description
The common mistake
Skipping the boring version. Get a simple end-to-end design on the board early, then improve it.
From public interview guides and candidate reports, not from Microsoft. The interviewer is an AI running in that style; it is practice, not a prediction.
Start the round
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