AWS data transfer costs often overlooked, become major expense at scale

Data transfer fees are the most commonly underestimated cost item in AWS budgets. While not the largest expense initially, they increase rapidly as systems scale and are difficult to reduce without architectural changes. Charges apply to internet egress, cross-region traffic, and movement between availability zones within a region. In microservices architectures spread across zones, frequent API calls generate significant cumulative billing. Organizations can mitigate costs by analyzing usage patterns, consolidating services, optimizing data placement, and using services like CloudFront.