The enterprise Mosquitto alternative for production IoT.
Eclipse Mosquitto is excellent for development and small deployments. When you need clustering, durable message delivery, AMQP support, and 100K+ connections, FluxMQ takes over where Mosquitto stops.
When does Mosquitto need an alternative?
Mosquitto is a single-node MQTT broker. It has no built-in clustering, no durable queues, and no AMQP support. Teams that need high availability, horizontal scaling beyond a single node, or guaranteed message delivery to consumer groups typically migrate to a distributed broker like FluxMQ.
What Mosquitto is good at.
Mosquitto is a mature, lightweight MQTT broker maintained by the Eclipse Foundation. It's the right tool for many use cases.
Fast to spin up, minimal config, runs everywhere. The standard choice for local development and integration testing.
The mosquitto C binary is lean enough to run on embedded
Linux systems with very limited resources.
For a single-site installation with a few hundred devices and no HA requirement, Mosquitto is simple and reliable.
Every MQTT client library on the planet has been tested against Mosquitto. It is the reference implementation.
Where Mosquitto hits its ceiling.
Mosquitto is a single-node broker. High-availability setups require external tooling — load balancers, shared state stores, or broker bridges — none of which Mosquitto manages itself.
Mosquitto has QoS 1/2 and retained messages but no durable queue semantics — consumer groups, offset tracking, dead-letter queues, or Kafka-style retention with replay.
Mosquitto speaks MQTT. If your architecture also has AMQP services (RabbitMQ consumers, SAP integrations, Azure Service Bus connectors), you need a separate broker for that traffic.
Mosquitto handles hundreds of thousands of connections on capable hardware but cannot distribute that load across multiple nodes natively. FluxMQ scales linearly by adding nodes.
FluxMQ vs Mosquitto — feature by feature.
| Feature | FluxMQ | Mosquitto |
|---|---|---|
| MQTT 3.1.1 & 5.0 | Yes | Yes |
| AMQP 0.9.1 | Yes | No |
| AMQP 1.0 | Yes | No |
| CoAP bridge | Yes | No |
| Built-in horizontal clustering | Yes (embedded etcd) | No |
| Durable message queues | Yes (consumer groups, DLQ) | No |
| Kafka-style retention | Yes | No |
| Raft-based replication | Yes | No |
| Per-IP & per-client rate limiting | Yes | Plugin required |
| mTLS inter-broker gRPC | Yes | N/A (no clustering) |
| Zero external dependencies | Yes (single Go binary) | Yes (single C binary) |
| License | Apache 2.0 | EPL 2.0 / EDL 1.0 |
Sources: Eclipse Mosquitto documentation (mosquitto.org), FluxMQ source code and documentation (github.com/absmach/fluxmq). Mosquitto plugin ecosystem can extend some features; table reflects out-of-the-box capabilities.
Built for what Mosquitto doesn't cover.
Same MQTT wire protocol. Full clustering, durable queues, and AMQP support added. Apache 2.0 for all features.
Moving from Mosquitto to FluxMQ.
Client code does not change. Any MQTT 3.1.1 or 5.0 client that connects to Mosquitto connects to FluxMQ without modification.
Run FluxMQ alongside Mosquitto
Start FluxMQ on the same network. Point a test client at FluxMQ on port 1883. Both brokers can run simultaneously during migration.
Validate client compatibility
Connect your existing MQTT clients to FluxMQ. QoS levels, retained messages, Last Will and Testament, and shared subscriptions all work as expected.
Cut over and enable clustering
Redirect clients to FluxMQ. When ready for HA, add cluster nodes in the YAML config. etcd handles coordination automatically.
Common questions.
Why do teams outgrow Mosquitto?
Mosquitto is a single-node broker. When deployments need high availability, horizontal scaling, or durable message delivery guarantees, Mosquitto cannot be extended without external orchestration. FluxMQ ships clustering, Raft replication, and durable queues out of the box.
Is FluxMQ a drop-in replacement for Mosquitto?
Yes for clients. Any MQTT 3.1.1 or 5.0 client that works with Mosquitto connects to FluxMQ without code changes — the wire protocol is identical. The operational difference is that FluxMQ is configured differently and adds AMQP, durable queues, and clustering on top.
Does FluxMQ support the same MQTT feature set as Mosquitto?
FluxMQ supports all standard MQTT 3.1.1 and 5.0 features including QoS 0/1/2, retained messages, Last Will and Testament, shared subscriptions, flow control, and user properties. MQTT 5.0 feature coverage is complete.
Can I run FluxMQ as a single node like Mosquitto?
Yes. FluxMQ runs as a single node with the same single-binary operational model as Mosquitto. Clustering is opt-in — add cluster peers in the YAML config when you are ready to scale.
What is the license difference?
Mosquitto is dual-licensed under the Eclipse Public License 2.0 and Eclipse Distribution License 1.0. FluxMQ is Apache 2.0. Both are open source. Apache 2.0 is generally considered more permissive for commercial use and integration into proprietary systems.
How does FluxMQ handle 500K+ concurrent connections?
FluxMQ uses zero-copy packet parsing, object pooling, and efficient trie-based topic matching to sustain high connection counts. Session ownership is tracked per broker node with sub-100ms session takeover when a node fails.
Ready to scale beyond Mosquitto?
FluxMQ is open source, Apache 2.0, and ships as a single Go binary. No external dependencies. Full clustering from day one.