RabbitMQ is a complete and highly reliable enterprise messaging system based on the emerging AMQP standard
Cost / License
- Free
- Open Source
Platforms
- Mac
- Windows
- Linux

Google Cloud Pub/Sub is described as 'Pub/Sub works as a messaging middleware for traditional service integration or a simple communication medium for modern microservices' and is an website. There are six alternatives to Google Cloud Pub/Sub, not only websites but also apps for a variety of platforms, including Windows, Linux, Self-Hosted, Mac and Snapcraft apps. The best Google Cloud Pub/Sub alternative is RabbitMQ, which is both free and Open Source. Other great sites and apps similar to Google Cloud Pub/Sub are Apache Pulsar, Amazon Simple Queue Service, Eclipse Mosquitto and ActiveMQ.
RabbitMQ is a complete and highly reliable enterprise messaging system based on the emerging AMQP standard

Apache Pulsar is a distributed, open source pub-sub messaging and streaming platform for real-time workloads, managing hundreds of billions of events per day.
Amazon Simple Queue Service (SQS) is a fast, reliable, scalable & affordable message queuing service. Use SQS to transmit data without losing messages.

Eclipse Mosquitto is an open source (EPL/EDL licensed) message broker that implements the MQTT protocol versions 5.0, 3.1.1 and 3.1. Mosquitto is lightweight and is suitable for use on all devices from low power single board computers to full servers.
Apache ActiveMQ is the most popular and powerful open source messaging and Integration Patterns provider.