A hiring manager's question bank for Node.js developers — the event loop, streams, async patterns, building APIs with Express, error handling, and security. Built to separate people who can call npm install from people who can keep a Node service healthy under load.
Hiring a Node.js developer is really about backend judgement expressed through one specific runtime. The thing that trips people up is that Node is single-threaded and event-driven, so a candidate who treats it like a traditional threaded server will write code that quietly blocks the event loop and tanks throughput for every other request. The strongest signal in a Node interview is whether someone understands that distinction in their bones: that synchronous work, a heavy JSON parse, or a tight CPU loop in a request handler stalls the whole process, and that the answer is offloading, streaming, or a worker — not more requests per second on faith. Beyond the runtime, you want to confirm they can build and structure a real API: middleware ordering, validation, consistent error handling, not leaking stack traces, and not blowing up memory by buffering a large file into RAM instead of streaming it. The questions below run from event-loop fundamentals through streams and async patterns into API design, error handling, and security, which mirrors how production maturity reveals itself. Listen for candidates who talk about backpressure, graceful shutdown, timeouts, and what happens when a downstream dependency is slow. Pair a couple of runtime questions with one API-design discussion and one "a Node service is using too much memory" scenario, and you will quickly learn whether someone has operated Node in production or only built a tutorial CRUD app.
Pick six to eight questions across two or three categories rather than the entire list. Start with an Event Loop & Runtime question to set a baseline, then move into an APIs & Architecture discussion and one Production scenario about errors, memory, or security. Push every clean answer with "what happens under load?" or "what if that downstream call hangs?" — that is where production experience shows.
JuggleHire goes beyond simple job posting. Leverage custom forms, powerful screening filters, and automated social media previews to find the perfect fit for your team.