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API Gateway is a great service but can be quite expensive, and even cost-prohibitive in some cases. Application Load Balancer is a viable alternative since it integrates seamlessly with Lambda functions and is highly scalable and reliable. For very small traffic, API Gateway will probably be the winner, but in high-throughput cases, ALB is capable of providing up to 90% savings. The opportunity to cut costs will depend on whether your API receives too many similar queries over short periods of time.