A Service Catalog is a centralized portal for tracking microservices. With access to a Service Catalog, developers get an integrated, developer-friendly view of all of the services in an application, regardless of where they are deployed.
Having access to this information enables application developers to quickly discover critical data about services during an outage and resolve issues faster.
As compared to the monolith, information about individual microservices becomes harder to find with distributed development and in a microservices architectures. Because of this, cloud native application developers tend to rely more heavily on service catalogs as key pieces of infrastructure.