FastPay service communication architecture integrates React frontends with Laravel 7-12 consumer/identity/commerce services and Java Spring Boot microservices across 20+ core domains. Data flows from web clients through REST APIs to backend services, with shared infrastructure including MySQL 8, MongoDB 6, Redis, MinIO, and observability via Graylog and Elasticsearch. This polyglot approach demonstrates how to coordinate multiple technology stacks—PHP Laravel, Java Spring Boot, React variants—while maintaining single responsibility across personal, merchant, billing, and switching domains. Fork this diagram on Diagrams.so to customize service ports, add deployment targets, or document your own multi-language microservices topology. The architecture supports 30+ telecom operators and external payment gateways, illustrating enterprise-scale service orchestration.