Your startup’s Next.js monolith is growing and some engineers want to split it into microservices. How do you decide, and what would you do?

What the interviewer wants to hear

• Identify the real pain: deploy speed, scaling, team ownership or reliability
• Microservices add network failures, distributed data and ops cost
• A modular monolith with clear boundaries is often the better first step
• Extract services only where scaling or ownership clearly needs it
• Use the strangler pattern and keep data ownership per service

Model answer

First I ask what problem we are actually solving. Slow builds, unclear ownership, one hot path that needs different scaling, or frequent outages caused by unrelated code all have different fixes. Microservices bring real costs: network calls that fail, distributed transactions, harder debugging, more deployment pipelines and the need for good observability. For a small team that cost usually outweighs the benefit. So my default is a modular monolith: clear domain modules such as billing, catalog and accounts, with explicit interfaces, no reaching into each other’s tables, and lint rules that enforce boundaries. If one part truly needs independent scaling or a separate team, like video processing or search indexing, I extract it using the strangler pattern behind a stable API, give it its own data, and communicate through events where possible. I measure whether the split improved the original pain.

More hard Full Stack Developer questions

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