Economics of Small Decisions
Thirty questions on the economics hiding inside ordinary choices — not interest rates and GDP, but the trade-offs you make every day. Covers opportunity cost, the sunk cost...
Quizzes
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English for Code Reviews
Practical English for pull requests and code reviews, organized as a small curriculum: commit subjects and PR titles, PR descriptions, the grammar that trips up non-native...
Everyday Physics Myths
Thirty-six everyday physics myths and half-truths — does a heavier object really fall faster, why is the sky blue, is there no gravity in space, and does the Coriolis effect...
Where Data Lives: Frontend Data-Fetching & State Architecture
The biggest architectural decisions in a modern frontend are about where data lives and when it's fetched. Start by separating server state (an async cache of data you don't...
Game Theory in Awkward Situations
Thirty-five questions on strategic behavior in everyday human situations — splitting the bill, replying late, group projects, salary talks, and office politics — using them to...
Hello, Goodbye, and Thank You Around the World
A globe-trotting, slightly silly tour of the three phrases every traveller actually needs — hello, goodbye, and thank you — across 40-plus languages. Each question pairs the...
Designing an HTTP API (REST, Done Right)
Most "REST" APIs are RPC in disguise. This quiz sharpens the decisions that matter when other people build against your endpoints: method safety and idempotency,...
Real-Time over HTTP/2 & HTTP/3: Multiplexing, QUIC & WebSocket Bootstrapping
How HTTP/2 multiplexing, HTTP/3 over QUIC, and Extended CONNECT (RFC 8441/9220) reshape real-time delivery: application- vs transport-level head-of-line blocking, QUIC's...
Idempotency, Retries & Delivery Guarantees
Networks fail mid-request, so real systems retry — and retries are where correctness quietly breaks. Build intuition for at-least-once vs. at-most-once vs. 'exactly-once' (and...
Master JavaScript Promise & Async Execution
Step through the event loop, microtask & macrotask queues, async/await suspension, and tricky async patterns. Detailed MDN-linked explanations reveal after every answer.
Message Delivery: Guarantees, Ordering & Idempotency
At-most-once vs at-least-once vs "exactly-once," why duplicates and gaps happen, and how idempotency, dedup, sequence numbers, and per-key ordering tame them. The...
Node.js Buffers & Binary Data
How Buffer, Uint8Array, ArrayBuffer, and DataView fit together; UTF-8 / hex / base64 encodings; byte order; which operations share memory versus copy; and why turning binary...