This question comes up a lot in modern engineering teams — especially when microservices scale beyond 10, 20, or 50+ services. At that stage, running full end-to-end tests becomes painful… long execution times, weird flakiness, environments breaking, dependencies getting out of sync, etc. So naturally people ask:
Can integration tests replace end-to-end tests entirely?
In short: No — but they can dramatically reduce how much E2E testing you need.
Integration tests do something incredibly valuable: they validate how multiple services behave together at a boundary level — usually at the API contract. They run faster, they’re easier to maintain, and they don’t need a fully deployed environment the same way E2E tests do. For microservices teams this is gold, because the main pain point is usually system complexity, not UI flows.
BUT — integration tests don’t capture full-stack real world flows like checkout, complete user journeys, or cross-domain side effects — the things only true E2E tests expose.
So the balance most high-scale orgs find is this:
Layer Amount
Unit tests tons
Integration tests lots
End-to-end tests a few, critical flows only
That last line is the key: E2E becomes surgical.
And today, tools like Keploy help automate creation of realistic integration tests using real production traffic — which means you can maintain high coverage without writing everything manually.