Guess the stack. Learn why it works.
Five questions a round, getting harder as you climb — "what does this real product actually run on, and why." After each round you choose: bank your points, or gamble them on a harder one. Every answer comes with the engineering reasoning behind it.
How a round works
A correct answer in round 7 is worth seven points, so climbing pays. But score fewer than two out of five in a round and you lose everything you were holding — knowing when to stop is half the game. No account needed, just a nickname for the board.
Easy
Well-known, widely reported choices — the kind of fact that shows up in any "how X was built" write-up.
Medium
Still documented, but more specific — a migration, a framework swap, a deliberate trade-off.
Hard
Infrastructure-level detail: the database, the queue, the in-house tool built to solve one particular problem.
From the stack directory
Short profiles of what real companies run, and why.
Netflix
Netflix's backend is a large ecosystem of Java-based microservices, supported by resilience tools like Hystrix, Eureka …
Twitter (X)
Twitter started on Ruby on Rails during its "fail whale" era, then moved much of its backend onto the JVM using Scala a…
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