Eclipse Mosquitto and EMQX both speak MQTT 5.0, 3.1.1 and 3.1, so on paper they look interchangeable. In practice they're built for very different jobs, and since EMQX 5.9.0 the licenses differ more than many people realize.
License
- Mosquitto is free open source under EPL-2.0 or EDL-1.0 (SPDX: EPL-2.0 OR BSD-3-Clause).
- EMQX unified its Open Source and Enterprise editions in v5.9.0 under the Business Source License 1.1. Production use on a single node is free, and each version converts to Apache-2.0 after four years.
Clustering and scale
- Mosquitto is lightweight and runs on anything from a low-power single-board computer to a full server. Bridges connect brokers together; high availability is a feature of Cedalo's commercial Pro Edition.
- EMQX has masterless clustering plus Cluster Linking across regions, and the project cites 100M+ concurrent MQTT clients in a single cluster.
Protocols and integrations
- Mosquitto offers listeners for MQTT, MQTT over WebSockets or an HTTP API. Core MQTT features are open source; integrations, REST APIs and persistent queuing are in the Pro Edition.
- EMQX adds MQTT over QUIC and gateways for MQTT-SN, CoAP and LwM2M, plus a SQL rule engine, Flow Designer and 50+ integrations (for example Kafka, PostgreSQL, MongoDB and InfluxDB).
Paid options and getting started
- Mosquitto has installers for Windows, Homebrew on macOS, and snap on Linux and Raspberry Pi, plus a public test broker at test.mosquitto.org. Cedalo sells the Pro Edition, hosted or on-prem instances and consulting; mosquitto.org lists no prices.
- EMQX Serverless starts at US$0/month for up to 1,000 connections, Dedicated Flex from US$234/month, and BYOC and Enterprise are custom-priced (as of Oct 2026).
Quick fit check
Pick Mosquitto if you want a small, permissively licensed broker for a pilot, an edge gateway or a single-board computer, and bridging a few brokers is enough (or you'll buy the Pro Edition when you need HA).
Pick EMQX if you need clustering, a rule engine and built-in integrations to Kafka, databases or cloud services in the broker itself, and a single production node under BSL is enough, or you want a managed broker with a free tier.
The full side-by-side table with every source link is on PlantWired: EMQX vs Mosquitto. Related: HiveMQ vs EMQX, HiveMQ vs Mosquitto, MQTT Sparkplug B explained, and The Unified Namespace (UNS) stack, explained with real tools.
Our data comes from public project and vendor pages and surely has gaps. If you run either in production and something's wrong, tell us in the comments and we'll fix it.
PlantWired is a free, vendor-neutral map of factory software. A short weekly brief on new integrations is at plantwired.vercel.app.
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