hardDesignScenarioSeniorStaffLead
How do you decide between a modular monolith and microservices?
4 min readUpdated 2026-08-15
Answer
Short answer
The choice turns on team topology and independent deployability, whether domain boundaries are stable, data ownership and distributed-transaction cost, and real operational maturity.
Was this answer helpful?
Likely follow-ups
- What signals in a running system would tell you a specific module is now worth extracting?
- How would you preserve a business invariant that used to be a single database transaction once it spans two services?
- How do you stop a modular monolith's internal boundaries from eroding over eighteen months?
- You have inherited forty services maintained by three teams. What do you do?
Related questions
- How do you decide where one service ends and the next begins, and when is a modular monolith the more honest answer?hardAlso on microservices and service-boundaries7 min
- How do you isolate a degraded dependency and halt a cascading failure before thread pool exhaustion takes down the entire microservice ecosystem?hardAlso on distributed-systems and microservices2 min
- A teammate says a saga can just roll everything back if step four fails. What is wrong with that, and what would you tell them to build instead?hardAlso on microservices5 min
- Walk me through applying STRIDE to the boundary where our order service calls the payments service over the network.mediumAlso on distributed-systems4 min