NestJS supports six built-in transports: TCP, Redis, NATS, MQTT, RabbitMQ (AMQP), Kafka, and gRPC. Bootstrap a standalone microservice with NestFactory.createMicroservice(). For a hybrid app that handles both HTTP and microservice messages in one process, use app.connectMicroservice() after NestFactory.create().
TCP — lightweight, direct socket communication; good for internal service-to-service calls.
Redis — uses Redis pub/sub; simple to set up; message loss possible if Redis restarts.
RabbitMQ (AMQP) — durable queues, exchanges, routing keys; most feature-rich broker.
Kafka — high-throughput distributed log; best for event streaming at scale.
gRPC — binary protocol over HTTP/2; best for high-performance typed inter-service calls.
Transport enum and MicroserviceOptions are exported from @nestjs/microservices.