Problems / Design a product, medium
Design Tinder from an empty canvas: profile cards of people nearby from a geospatial index, write-heavy swipes, match detection and chat.
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Request types to route: swipe (65%, write), cards (25%, read), chat (10%, write). Budget: $12,000 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 ≥ 99.9%; p99 latency ≤ 150 ms (swipe); p99 latency ≤ 300 ms (cards) |
| Sunday evening | At 5 s Sunday evening arrives: traffic triples for 8 s. | Success ≥ 99%; p99 latency ≤ 300 ms (swipe) |
| Cache flushed | At 5 s the cache on the request path is emptied, as after a restart or a bad deploy. | Success ≥ 99% |
| A server dies | At 4 s one server of the first app service on the request path dies for 10 s. | Success ≥ 99% |
| Budget: $12,000/month | The normal day's design must cost at most $12,000 a month. | Cost ≤ $12,000/month |