Senior (L5) · System design

Senior Backend Engineer

Senior loops check that you can design a complete, scalable system end to end, choose sensible storage and messaging, and handle the obvious failure modes without prompting.

How the loop runs

Roughly 37 minutes across three rounds.

1. 1

   High-level design

   15 min

   Requirements, API, data model, core components

2. 2

   Chaos injection

   12 min

   Node failure, reconnect storms, hot partitions

3. 3

   Cost & edge cases

   10 min

   Capacity estimates and operational trade-offs

Where candidates lose points

• Skipping capacity estimates
• One database for everything with no partitioning plan
• No plan for reconnects or retries