Apache ActiveMQ
Details of “classic” ActiveMQ’s support for MQTT are available here.
Apache ActiveMQ Apollo
The “next generation” of ActiveMQ, Apache Apollo, supports MQTT via a plugin.
Apache ActiveMQ Artemis
Artemis is a multi protocol messaging broker that supports MQTT.
Bevywise MQTTRoute
MQTTRoute is a highly secure, high performance broker. The MQTT Broker is written in C & Python and works with all standard MQTT Clients. MQTTRoute has a FREE and affordable premium version.
Emitter
Emitter is clustered and open-source MQTT broker, written entirely in Go. It proposes several additional features on top of a traditional MQTT broker, as it includes custom per-topic security and shared-nothing scalable architecture which helps you avoid single points of failure. Full source-code available on GitHub.
emqttd
emqttd is a distributed, massively scalable, highly extensible MQTT message broker written in Erlang/OTP. emqtt.io / @emqtt
emqttd is fully open source and licensed under the Apache Version 2.0. EMQ implements both MQTT V3.1 and V3.1.1 protocol specifications, and supports MQTT-SN, CoAP, WebSocket, STOMP and SockJS at the same time.
emqttd provides a scalable, reliable, enterprise-grade MQTT message Hub for IoT, M2M, Smart Hardware and Mobile Messaging Applications. The 1.0 release of the emqttd broker has scaled to 1.3 million concurrent MQTT connections on a 12 Core, 32G CentOS server.
Eurotech Everywhere Device Cloud
Eurotech Everywhere Device Cloud is a cloud-based service provided by Eurotech.
flespi
flespi is a cloud-based MQTT broker service. High-volume targeted architecture, isolated MQTT namespace, WebSockets/SSL support, 1-click account registration, commercial and free SLA, managed by HTTP REST API. See MQTT API FAQ for more information.
HBMQTT
HBMQTT is an open-source implementation of MQTT broker and client. It uses Python 3.4+ asyncio library for providing a mono-threaded, non-blocking implementation of the protocol.
HiveMQ
HiveMQ is a MQTT broker which was built from the ground up with maximum scalability and enterprise-ready security in mind. It comes with native web socket support and an open source plugin SDK to extend its functionality or integrate it with other components. A public test server is also available (more information).
IBM Integration Bus
IBM Integration Bus V9 has Telemetry feature built-in as optional licensed feature. IBM WebSphere MessageBroker V7 & V8 also include it as optionally licensed feature.
Really Small Message Broker 75KB MQTT broker runtime free download as binaries from IBM alphaWorks, RSMB is a C implementation of a tiny MQTT server suitable for development, embedded systems, concentrators or small to medium sized deployments. It provides complete MQTT v3.1 support, bridging, and a C client API.
IBM MessageSight
IBM MessageSight is a DMZ secure MQTT appliance with hardware messaging acceleration for M2M and mobile applications requiring extreme volume, low latency, FIPS 140-2 and NSA Suite B security. Messaging provider for MQTT, HTML5 WebSockets, JMS. Includes C, Java, JavaScript, Apache Cordova/PhoneGap, ObjectiveC clients. Also connects/bridges IBM MQ, IBM Integration Bus, WebSphere MessageBroker.
IBM Websphere MQ Telemetry
The Telemetry MQTT feature is built-in optionally licensed feature in WebSphere MQ version 7.1 and above. It provides full MQTT v3.1 support, IBM MQ and JMS support. IBM WebSphere MQ Advanced includes the MQTT license at no charge. It ships with reference Java (MIDP and above), C and JavaScript (MQTT over WebSocket) clients.
JoramMQ
JoramMQ is an offering by ScalAgent providing a message broker that fully supports MQTT 3.1, JMS 2.0, and AMQP 1.0. Interoperability between these standards is ensured by the message broker. MQTT can be used over TCP/IP, TLS (SSL), WebSocket, and secure WebSocket. JoramMQ is particularly appropriate for applications that need to scale with the number of MQTT clients while allowing the publishers to reliably transmit a large volume of messages with a low latency.
Litmus Automation Loop
Loop is a cloud based MQTT broker with scalability, high availability and security at core. Loop provides full MQTT 3.1 support and JMS connectivity. It can handle extremely large numbers of connected clients. On the other side it can be connected to any ERP, CRM and enterprise architecture with ESB or NoSQL databases for blazing fast data storage.
Moquette
Moquette is a Java MQTT broker based on an eventing model with Netty.
Mosca
As node.js MQTT broker can Mosca be plugged on top of Redis, AMQP, MQTT, or ZeroMQ.
Mosquitto
Mosquitto is an Open Source MQTT server. A public, hosted test server is also available (more information)
MQTTnet
MQTTnet is a .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker).
RabbitMQ
RabbitMQ is an AMQP message broker – with an MQTT plugin (bundled in version 3.x onwards). A public test server is also available (more information).
Solace
Solace Message Routers (available as hardware and software) are message brokers that support MQTT, JMS, and REST among other APIs, protocols and qualities of service for enterprise messaging, data collection and web/mobile streaming. They support very high connection counts and throughput with built-in buffering to handle bursty traffic, and offer enterprise-class monitoring, high availability and security.
ThingScale IoT message broker
ThingScale IoT message broker is a fully-managed IoT messaging service provided by Sensinics,LLC. ThingScale provides a messaging system for IoT connected devices. The API is used to retrieve events, users, devices, sessions, and channels in JSON format. ThingScale supports TLS payload encryption, scheme-less and cyclic data sampling, and trigger-based notifications. A 30days trial license is offered free of charge. MQTT is the preferred messaging protocol. Dev Portal& API Portal
VerneMQ
VerneMQ is an enterprise ready, high-performance, distributed MQTT message broker. It scales horizontally and vertically on commodity hardware to support a high number of concurrent publishers and consumers while maintaining low and predictable latency and fault tolerance. VerneMQ plugins can be developed in Erlang, Elixir, Lua, and any programming language that can implement HTTP WebHooks. VerneMQ uses modern broadcast protocols and LevelDB for state replication in a cluster. VerneMQ is Open Source and Apache2 licensed.
Vert.x MQTT Broker
Vert.x MQTT Broker is an open-source implementation of MQTT server. It implements protocol versions 3.1.1 and 3.1, supports QoS 2, and uses OAuth2 for autentication. It uses vert.x as library for tcp managemnet, non-blocking / actor-model, clustering and auth plugin system.
Yunba.io
Yunba is a backend cloud platform that provides real-time message dispatch service to mobile applications and devices and uses MQTT as a transport protocol, The services include bi-directional push for Instant-Messaging; real-time analyzing; real-time online monitoring.