EMQX vs Google Cloud Pub/Sub

EMQX is an MQTT messaging platform for connecting, moving, and processing IoT business data in real time. EMQX Enterprise combines publish/subscribe messaging with durable message queuing, while a SQL-based Rule Engine and visual Flow Designer support filtering, transforming, enriching, and routing data. The platform supports MQTT and protocols or gateways including QUIC, CoAP, STOMP, and LwM2M; its listed protocols also include MQTT-SN, OCPP, GB/T 32960, JT/T 808, and NATS. EMQX says a cluster can handle up to 100 million concurrent MQTT connections and lists more than 50 native integrations. Security features include TLS/mTLS, X.509 authentication, access controls, and audit logs. Deployment options include Docker, a Kubernetes Operator, and installation packages, with macOS and Linux packages listed. Plans include free Serverless and Dedicated Flex starting at $234 per month, with a 14-day trial listed for Dedicated Flex. Serverless has limits including 1,000 sessions, 1,000 TPS, and a 1 MB message size.

Google Cloud Pub/Sub is a cloud messaging service for asynchronous communication between services that produce messages and those that process them. It is intended for service-to-service use, including streaming analytics, data integration, middleware, and parallel task queues, rather than direct communication with end users or IoT clients. Communication typically has latency around 100 milliseconds. Synchronous cross-zone replication and per-message receipt tracking provide at-least-once delivery; Dataflow supports exactly-once processing of Pub/Sub streams. There are no shards or partitions, and provisioning scales automatically after quota is set. Message controls include seek and replay, dead letter topics, and attribute-based filtering. Pub/Sub offers fine-grained access controls, end-to-end encryption, and HIPAA compliance. It supports REST and gRPC APIs and client libraries for seven languages; API keys are not supported for authentication. The maximum message size is 10 MB. The free monthly tier is free for the first 10 GB of data per month. Pay-as-you-go is $40 a month beyond 10 GB, with throughput listed at $40 per TB and storage at $0.27 per GiB-month.