Top 3 Open Source MQTT Brokers for Industrial IoT in 2025

As Industrial IoT (IIoT) and Industry 4.0 technologies become standard, the need for a robust and efficient communication protocol is more critical than ever. The MQTT broker has emerged as the clear leader, acting as the central nervous system for connecting everything from PLCs to cloud platforms. With so many options available, how do you decide which one is right for your project？

This article provides a comprehensive and up-to-date analysis of the three leading open-source MQTT brokers for IIoT in 2025. We will break down their features, performance, and ideal use cases to help you build a Unified Namespace (UNS) architecture for your modern, high-performance industrial system.

At a Glance: The Top 3 Open-Source IIoT MQTT Brokers

To help you find the ideal solution for your IIoT project, we've selected three leading open-source MQTT brokers based on their community health, project activity, and suitability for modern industrial applications and resource-constrained environments.

• EMQX: Still the most-starred MQTT broker on GitHub, with over 15k stars. It's renowned for its robust, scalable architecture and rich enterprise features. It has a booting footprint of 50M and supports clustering capabilities.
• Mosquitto: Continues to be the most widely adopted MQTT broker, prized for its simplicity and minimal footprint of less than 1M in a single-threaded architecture.
• NanoMQ: One of the fastest-growing and most active MQTT broker projects, known for its multi-threading and async-io support. It has superior performance on resource-constrained devices with a startup space of about 2M.

Here is a summary of the 3 projects hosted on GitHub:

1. EMQX

EMQX is a highly scalable, distributed MQTT broker for enterprise IIoT deployments. It offers extensive support for MQTT 5.0, MQTT-SN, SSL/TLS encryption, and MQTT over QUIC. It further enables masterless clustering to achieve high availability and horizontal scalability.

With an impressive 15.1k stars on GitHub, EMQX has established itself as one of the most popular MQTT brokers available. The EMQX project was launched in 2012 and is licensed under Apache version 2.0(EMQX 5.8 and earlier versions). EMQX is written in Erlang/OTP, a programming language for building massively scalable soft real-time systems.

EMQX is suitable for deployment in the cloud and on the edge. At the edge, it can integrate with various industrial gateways such as N3uron, Neuron, and Kepware. In cloud environments, EMQX offers seamless integration with a range of technologies, including Kafka, databases, and cloud services, on leading public cloud platforms like AWS, GCP, and Azure.

With comprehensive enterprise-grade features, data integration capabilities, cloud hosting services, and commercial support from EMQ Technologies Inc, EMQX is widely used for mission-critical applications in the IIoT domain. In 2025, EMQX's focus on AIoT integration and enhanced data processing at the edge sets it apart.

Advantages

• Masterless clustering and high availability
• High-performance and low latency
• Rich authentication mechanism
• Edge-to-cloud deployment
• Pioneering MQTT over QUIC
• AIoT & Data Integration

Disadvantages

• Complex to set up and configure
• High CPU/Mem usage

Use Cases

• Automotive manufacturing
• Iron and steel manufacturing
• Oil & Gas
• Semiconductor manufacturing
• Water supplies

2. Mosquitto

Mosquitto is a widely used open-source MQTT broker under the Eclipse Foundation, licensed under the Eclipse Public License (EPL/EDL license). As of August 2025, it has over 10k stars on GitHub. It implements MQTT protocol versions 5.0, 3.1.1, and 3.1 and supports SSL/TLS and WebSocket.

Mosquitto is written in C/C++ and uses a single-threaded architecture. Its lightweight design makes Mosquitto suitable for deployment on embedded devices or industrial gateways with limited resources. Mosquitto is cross-platform and can run on various platforms, including Linux, Windows, and macOS.

Advantages

• Lightweight and small footprint
• Simplicity and easy to use

Disadvantages

• Without multi-threading and clustering support
• Not suitable deployment in the cloud

Use Cases

• Factory Automation
• Smart Manufacturing
• Smart Hardware

3. NanoMQ

NanoMQ is the latest open-source MQTT broker project released in 2020. NanoMQ is implemented in pure C, based on NNG's asynchronous I/O with a multi-threading Actor Model. It fully supports MQTT version 3.1.1 and 5.0, SSL/TLS, and MQTT over QUIC.

One of NanoMQ's standout features is its lightweight and fast nature with a minimal memory footprint. This makes it an exceptional MQTT broker for IIoT applications, where efficiency and resource optimization are paramount. Additionally, NanoMQ can work as a messaging gateway that converts protocols such as DDS, NNG, and ZeroMQ to MQTT and then bridges the MQTT messages to the cloud.

NanoMQ is highly compatible and portable, relying only on the native POSIX API. This makes deploying on any POSIX-compatible platform easy and runs smoothly on various CPU architectures, including x86_64, ARM, MIPS, and RISC-V.

Advantages

• Multi-threading and Async IO
• Small booting footprint
• Bridging with brokerless protocols

Disadvantages

• Project in early stage
• No clustering support

Use Cases

• Automotive Manufacturing
• Robotics: Edge service convergence
• IIoT Edge Gateway

Side-by-Side Comparison

The following chart shows a side-by-side comparison of the top 3 open-source MQTT brokers:

Optimize Broker Deployment for IIoT Projects: The Unified Namespace (UNS)

In the world of IIoT and Industry 4.0, the Unified Namespace (UNS) has emerged as a critical architectural pattern. UNS provides a consistent naming convention for all MQTT topics and data, breaking down data silos between devices, systems, and applications to truly achieve IT/OT convergence.

These three MQTT brokers can work together to form a robust UNS architecture. A typical deployment model looks like this:

• Edge Layer: Deploy lightweight, high-performance Mosquitto or NanoMQ on industrial gateways. They act as data collectors, gathering data from field devices (PLCs, sensors) and publishing it locally while using MQTT Bridges to forward data to the cloud.
• Hub Layer: Deploy a scalable and feature-rich EMQX in the cloud or enterprise data center. It serves as the data hub, aggregating all data streams from edge brokers, performing advanced processing, authentication, and routing, and integrating seamlessly with enterprise systems like Kafka, databases, and ERP/MES.

Conclusion: Choosing the Right MQTT Broker for Your IIoT Project

Each MQTT broker offers distinct strengths for different deployment scenarios.

• EMQX is the ideal choice for cloud-based IIoT deployments that require massive scalability, robust security, and advanced data integration.
• Mosquitto and NanoMQ are top-tier solutions for industrial gateways and edge computing, with NanoMQ offering a performance edge and Mosquitto a simplicity and stability advantage.

These three MQTT brokers are essential for modern industrial applications, driving the implementation of the UNS architecture and the convergence of IT and OT domains. When selecting a broker, consider your project’s scale, resource constraints, and integration needs to build a powerful, cohesive system.

Related Resources

• MQTT Broker: How It Works, Popular Options, and Quickstart
• Free MQTT Broker: Exploring Options and Choosing the Right Solution
• Mastering MQTT: The Ultimate Beginner's Guide for 2025
• MQTT Client Tools 101: A Beginner's Guide
• Unified Namespace (UNS): Architecture, Benefits & Solution
• MQTT Sparkplug: Bridging IT and OT for IIoT in Industry 4.0
• Siemens PLC and MQTT Integration: A Step-by-Step Guide