How AMEX Processes Millions of Daily Transactions With Millisecond Latency

American Express processes millions of transactions daily with millisecond latency by overhauling its payment system in 2018. Moving from legacy infrastructure to a modern cloud-ready system improved scalability, flexibility, and security. The key component, Global Transaction Router (GTR), uses Go language for concurrency, gRPC over HTTP/2 for faster internal communication, and asynchronous logging for performance optimization. Profiling, benchmarking, reader-writer mutexes, and avoiding excessive Go channels are some strategies employed to maintain high transaction processing speed and low latency.