Problems / Design a product, hard
Design Uber’s dispatch from an empty canvas: thousands of driver location updates a second, riders matched to a nearby driver in seconds, and trip state for both phones.
Unlock it once for 25 credits; everything inside it is free (runs, changes, Submit, results, hints). Sign in with Google to start; new accounts get free credits.
Request types to route: locate (80%, write), status (17%, read), request (3%, write). Budget: $10,000 a month.
You start from an empty canvas. When you run the tests, each one simulates your design with its own traffic and failures:
| Test | What it does | Passes when |
|---|---|---|
| Normal day | The normal day: the traffic in the brief, nothing broken. | Success ≥ 99.5%; p99 latency ≤ 150 ms (locate); p99 latency ≤ 200 ms (status); p99 latency ≤ 1.5 s (request) |
| New Year’s Eve surge | At 5 s it is midnight on New Year’s Eve: traffic jumps to 3× for 8 s. | Success ≥ 99%; p99 latency ≤ 300 ms (locate); p99 latency ≤ 2.5 s (request) |
| A server dies | At 4 s one server of the first app service on the request path dies for 10 s. | Success ≥ 99% |
| Database 5× slower | At 5 s the main database on the request path answers 5× slower for 8 s. | Success ≥ 99%; p99 latency ≤ 80 ms (status) |
| Budget: $10,000/month | The normal day's design must cost at most $10,000 a month. | Cost ≤ $10,000/month |