The Internet of Things (IoT) ecosystem in 2025 is more dynamic than ever. Connected devices—from smart home appliances to industrial monitoring systems—have proliferated, demanding secure and efficient data communication channels. One protocol has remained at the heart of these IoT deployments: MQTT (Message Queuing Telemetry Transport).
A crucial piece of any MQTT-based architecture is the MQTT broker, which routes messages between publishers and subscribers. In this blog post, we explore Open-Source MQTT Brokers—highlighting five standout solutions, discussing their key features, and comparing how they stack up across various use cases.
Why Open-Source MQTT Brokers Matter
Open-Source MQTT Brokers have steadily gained popularity due to their flexibility, transparency, and active community support. Whether you’re deploying on a small embedded device or orchestrating an entire enterprise IoT solution, these brokers provide:
- Cost Effectiveness – No licensing fees and the freedom to modify source code.
- Community-Driven Innovation – Rapid development cycles, timely patches, and expansive plugin ecosystems.
- Scalability – Ability to handle anything from a handful of devices to millions of concurrent connections.
1. Eclipse Mosquitto
Overview:
Eclipse Mosquitto, a project under the Eclipse Foundation, has been a go-to choice for IoT enthusiasts and professionals for over a decade. Its lightweight footprint and standards compliance make it a favorite for both small-scale and enterprise deployments.
Key Features:
- Lightweight and Fast: Consumes minimal resources, perfect for constrained environments.
- MQTT 3.1.1 and MQTT 5.0 Support: Ensures compatibility with the latest standards.
- Security and Authentication: Offers SSL/TLS encryption and username/password auth.
- Bridging: Connect multiple brokers to scale or segregate traffic.
- Active Community: Backed by the Eclipse Foundation and a dedicated network of contributors.
Ideal Use Cases:
- Hobby projects, proof-of-concepts, small business IoT setups, and cloud deployments where ease of setup is paramount.
2. EMQX
Overview:
EMQX (formerly EMQ) has evolved into one of the most powerful Open-Source MQTT Brokers in the market. Written in Erlang/OTP, EMQX offers massive scalability and fault-tolerance out of the box, handling millions of concurrent connections.
Key Features:
- High Throughput & Scalability: Erlang’s concurrency model excels at large-scale messaging.
- Multi-Protocol Support: Alongside MQTT, supports MQTT-SN, CoAP, WebSocket, and more.
- Extensive Plugin System: Plugins for databases (Redis, MySQL, PostgreSQL) and auth backends (LDAP, JWT).
- Dashboard & Monitoring: Real-time metrics and built-in observability.
- MQTT 5.0 Implementation: Leverages advanced features like Shared Subscriptions and Topic Aliases.
Ideal Use Cases:
- Large-scale industrial IoT deployments, smart city infrastructures, and enterprise applications needing horizontal scaling.
3. VerneMQ
Overview:
VerneMQ is another Erlang-based broker known for high availability and scalability. It uses a masterless clustering architecture, ensuring no single node is a bottleneck or point of failure. VerneMQ’s strong focus on security, stability, and extensibility makes it perfect for mission-critical IoT deployments.
Key Features:
- Masterless Clustering: Seamless scaling without downtime.
- Pluggable Authentication/Authorization: Customizable security via Lua hooks or external databases.
- MQTT 5.0 Compliant: Supports advanced features like user properties and message expiry.
- Session Persistence: Retains subscriber state even during node outages.
- Operational Insight: Detailed logging, tracing, and performance metrics.
Ideal Use Cases:
- Use cases demanding zero-downtime upgrades, large message volumes, and robust fault tolerance.
4. HiveMQ Community Edition
Overview:
HiveMQ has a strong reputation in the commercial MQTT world. Its Community Edition (CE) brings many enterprise-grade features to the open-source arena. Built in Java, HiveMQ CE focuses on reliability, performance, and developer-friendly integrations.
Key Features:
- Stable Core: Inherits proven enterprise reliability, now available for open-source usage.
- Plugin Framework: Extend broker functionality via Java-based plugins.
- Clustering for High Availability: Basic clustering in CE, with more advanced features in the commercial edition.
- Developer-Friendly Tooling: Comprehensive documentation and built-in metrics.
Ideal Use Cases:
- Medium to large-scale IoT setups that prefer Java’s ecosystem and may consider upgrading to a commercial edition later.
5. RabbitMQ (with MQTT Plugin)
Overview:
RabbitMQ is famous for AMQP (Advanced Message Queuing Protocol) but offers an MQTT plugin that transforms it into a hybrid messaging system. This approach is attractive for teams that need a unified messaging solution under a single broker.
Key Features:
- Unified Messaging: Supports multiple protocols like AMQP, MQTT, STOMP, and more.
- Clustering & Federation: Robust clustering model and federation for geo-distributed deployments.
- Plugins & Extensions: Extensive library for authentication, monitoring, and queue management.
- Enterprise Ecosystem: Large user base and well-established tooling, especially for AMQP workflows.
Ideal Use Cases:
- Organizations already using RabbitMQ who want to consolidate MQTT with other messaging protocols.
- Hybrid environments that demand multiple protocols under one roof.
Feature Comparison Table
Below is a high-level comparison of these Open-Source MQTT Brokers in key areas:
| Broker | Installation Guides | Language | License | Clustering | MQTT Versions | Scalability | Extensibility | Suitable For |
|---|---|---|---|---|---|---|---|---|
| Mosquitto | 1. Raspberry Pi 2. Ubuntu 3. Android | C | EPL/EDL (Eclipse) | Bridging (not a full cluster) | 3.1.1 & 5.0 | Moderate (lightweight) | External plugins/hooks | Small to mid-scale IoT, hobbyists |
| EMQX | 1. Raspberry Pi | Erlang/OTP | Apache 2.0 | Masterless cluster | 3.1.1 & 5.0 | Massive (millions) | Rich plugin ecosystem | Large-scale enterprise, industrial IoT |
| VerneMQ | 1. Ubuntu | Erlang/OTP | Apache 2.0 | Masterless cluster | 3.1.1 & 5.0 | Massive (millions) | Lua-based extensions, plugins | High availability, fault-tolerant setups |
| HiveMQ CE | General Guide | Java | Apache 2.0 | Basic clustering (more in commercial) | 3.1.1 & 5.0 | High | Java plugin framework | Commercial IoT, large-scale Java shops |
| RabbitMQ | 1. Raspberry Pi | Erlang | MPL 2.0 | Traditional clustering & federation | 3.1.1 & 5.0 (plugin) | High | Plugin-based architecture | Hybrid protocols, enterprise messaging |
Conclusion
By carefully evaluating the Open-Source MQTT Brokers listed above, you can match the right solution to your project’s unique demands—whether it’s a home automation project with modest needs or a large-scale industrial IoT deployment handling millions of messages per second. Here’s a quick recap:
- Eclipse Mosquitto: Lightweight, easy to set up, ideal for smaller or moderate IoT deployments.
- EMQX: Highly scalable, fault-tolerant, and feature-rich for large enterprises and industrial scenarios.
- VerneMQ: Focuses on high availability and masterless clustering, suitable for mission-critical use cases.
- HiveMQ CE: A robust Java-based solution with an easy upgrade path to enterprise features.
- RabbitMQ (with MQTT Plugin): Perfect if you need a unified broker for different protocols (AMQP, STOMP, MQTT).
Consider factors like deployment size, security requirements, cloud vs. on-premises setup, and existing infrastructure when choosing your broker. With the growing IoT landscape in 2025, selecting the right Open-Source MQTT Brokers will ensure reliable, scalable, and future-proof messaging for your devices and applications.
My Choice
As a DIY enthusiast I’ll choose Eclipse Mosquitto is usually the first pick. Why? It’s simple to install, doesn’t hog resources, and even runs smoothly on basic hardware like Raspberry Pi. It’s lightweight, easy to tweak, and perfect for stuff like home automation or small prototypes. If you just want something that works fast without a headache, Mosquitto is the right choice.