Amazon MQ vs Google Cloud Pub/Sub

Amazon MQ is a managed message broker service for Apache ActiveMQ and RabbitMQ. AWS handles broker provisioning, setup, upgrades, operation, maintenance, and failure recovery, while existing broker applications can migrate through standard messaging protocols without rewriting messaging code. Brokers can be launched from the AWS Management Console, CloudFormation, CLI, or API calls. Deployment options include single-instance, replicated-cluster, and active/standby modes, with availability and durability features across Availability Zones. ActiveMQ supports JMS, NMS, AMQP, STOMP, OpenWire, WebSocket, and MQTT, with clients for Java, Node.js, Go, Python, Ruby, and C++. RabbitMQ supports classic, classic mirrored, and quorum queues; quorum queues require RabbitMQ 3.13 or newer. CloudWatch receives broker and queue metrics every minute, and CloudTrail records related API calls. Data at rest uses AWS KMS encryption and broker connections use TLS; TLS 1.3 is unavailable for RabbitMQ brokers. Brokers can run inside an Amazon VPC, with private connections across VPCs and accounts for RabbitMQ. The service supports dead-letter queues, per-queue ordering, and configurable delivery guarantees. It is paid, with an AWS Free Tier plan for eligible new customers for six months; pay-as-you-go broker usage is hourly and storage monthly, with standard transfer fees potentially applying.

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.