containerization , Cassandra, PostgreSQL, Kafka, Spring Boot, OpenStack, MySQL, Swagger, Flask, Nestjs, Python, Java, Express, Node.js, Spring Cloud, Rabbitmq, API versioning, MongoDB, FastAPI, Kubernetes, RESTful service design, API-first design, Service-to-service communication, Fastify, Microservices architecture, SQL databases, OpenAPI specifications, DevOps practices, NoSQL databases