Engineering Lab
How I'd Build This
Architecture prompts with no single right stack. Each choice has strengths, weaknesses, and operational cost.
Al Beltran Engineering Lab
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How the challenge works
- Pick one option per layer. There is no single correct stack.
- The diagram and the notes update from your choices. Strengths and weaknesses are both real.
- The closing note is how I would steer a first version — not a claim about a specific employer system.
Key concepts
Hot path vs async path
If a user is waiting, do less. Counts, mail, and fan-out can be late.
Ops is a requirement
A beautiful store you cannot run is a worse design than a boring one you can.
Common mistakes
- Choosing Cassandra because it sounds like scale.
- Writing analytics on the request that has to be fast.
Interview tips
- Name QPS, payload size, and who pages before you name a brand.
- Say what you would change at 10×. That is the design.
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Built by Al Beltran