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Comparison of Open Source MQTT Brokers 2023

Fan Wang
Apr 25, 2023
Comparison of Open Source MQTT Brokers 2023

Introduction

MQTT (Message Queue Telemetry Transport), originally designed as a lightweight publish/subscribe messaging transport, is now the de facto standard messaging protocol for the Internet of Things (IoT). An MQTT Broker is critical in connecting clients, such as IoT devices, and moving MQTT messages between them.

publish/subscribe

As a16z said over a decade ago, "Software is eating the world." Open source is eating up software. More than 20 open-source MQTT broker implementations are available today, making the selection process challenging for software architects and developers.

In this post series, we’ll explore the top open-source MQTT brokers in 2023 and compare them in-depth to help you choose the best one for your needs.

Evaluation Criteria: Community and Popularity

To thoroughly compare open-source MQTT brokers in 2023, it is essential to consider the following evaluation criteria:

  • Community: evaluated by the number of GitHub stars, contributors, and issues.
  • Popularity: evaluated by examining the user base, downloads, and docker pulls.
  • Project Activity: evaluated the frequency of GitHub commits, PRs, and releases, especially those made within the last 12 months.

Based on the criteria, we choose to focus on four popular open-source MQTT brokers that have the most influence in the open-source community:

  • EMQX: This is the most starred MQTT broker on GitHub, with 11.4k stars.
  • Mosquitto: This is the second-most-starred but the most prevalent among MQTT brokers.
  • NanoMQ: This is the latest and one of the most active MQTT brokers available.
  • VerneMQ: Although not actively developing on Github, this MQTT broker has the third-highest number of stars.

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

EMQX Mosquitto NanoMQ VerneMQ
GitHub Project EMQX GitHub Mosquitto GitHub NanoMQ GitHub VerneMQ GitHub
Project Created 2012 2009 2020 2014
License Apache Version 2.0 EPL/EDL License MIT License Apache Version 2.0
Programming Language Erlang C/C++ C Erlang
Latest Release v5.0.23 (April 2023) 2.0.15 (Aug 2022) v0.17.0 (March 2023) v1.12.6.2 (Nov. 2022)
GitHub Stars 11.5k 7.2k 800+ 3k
GitHub Commits 14k+ 2800+ 2000+ 2400+
GitHub Commits (Last 12 Months) 3000+ 500+ 1200+ 50+
GitHub Issues 3500+ 2200+ 120+ 1300+
GitHub Releases 260+ 60+ 75+ 40
GitHub PRs 6000+ 600 780+ 600
GitHub Contributors 100+ 110+ 20+ 50

Overview of Top Open Source MQTT Brokers

EMQX

EMQX is one of the most popular MQTT brokers and has 11.5k stars on GitHub. The EMQX project was launched in 2012 and is licensed under Apache version 2.0. EMQX is written in Erlang/OTP, a programming language for building massively scalable soft real-time systems.

EMQX is the world's most scalable MQTT broker that supports advanced features such as MQTT 5.0, MQTT-SN, and MQTT over QUIC. It supports masterless clustering for high availability and horizontal scalability. EMQX 5.0, the latest version, scales to establish 100 million concurrent MQTT connections with a single cluster of 23 nodes.

See: Reaching 100M MQTT connections with EMQX 5.0

MQTT Cluster

EMQX offers rich enterprise features, data integration, cloud hosting services, and commercial support from EMQ Technologies Inc. Over the years, EMQX has gained popularity among enterprises, startups, and individuals due to its performance, reliability, and scalability. EMQX is widely used for business-critical applications in various industries, such as IoT, industrial IoT, connected cars, manufacturing, and telecommunications.

Official Website: https://www.emqx.io/

GitHub: https://github.com/emqx/emqx

Pros:

  • Supports large-scale deployments
  • High availability
  • Horizontal scalability
  • High-performance and low-latency
  • Rich enterprise features
  • Pioneering MQTT over QUIC

Cons:

  • Complex to set up and configure
  • Difficult to manage effectively
  • Logs may be confusing
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Mosquitto

The Mosquitto project was initially developed by Roger Light in 2009 and later donated to the Eclipse Foundation, licensed under the Eclipse Public License (EPL/EDL license). As of March 2023, it is the most widely deployed open-source MQTT broker with a large community and over 7k GitHub stars.

Mosquitto is written in C/C++ and uses a single-threaded architecture. Mosquitto implements MQTT protocol versions 5.0, 3.1.1, and 3.1, and supports SSL/TLS and WebSocket. Its lightweight design makes Mosquitto suitable for deployment on embedded devices or servers with limited resources.

Mosquitto is known for its small booting footprint of about 200k. However, it does not provide native support for multi-threading or clustering. Mosquitto is available for various platforms, including Linux, Windows, and macOS.

Mosquitto

Official website: https://mosquitto.org/

GitHub: https://github.com/eclipse/mosquitto

Pros:

  • Easy to setup and use
  • MQTT 5.0 protocol support
  • Lightweight and small footprint
  • Active community support

Cons:

  • Single-threaded architecture
  • Limited scalability in production ( <100k )
  • No clustering support
  • Lacking enterprise features
  • Limited cloud-native support

NanoMQ

NanoMQ, an open-source project released in 2020, is a lightweight and fast MQTT messaging broker designed for edge computing scenarios in the Internet of Things (IoT).

NanoMQ is implemented in purely C, based on NNG's asynchronous I/O with a multi-threading Actor Model. It fully supports MQTT 3.1.1 and MQTT 5.0 protocol versions and pioneers MQTT over QUIC.

NanoMQ is lightweight and high-performance, making it suitable for various edge computing platforms. It is highly compatible and portable, relying solely on the native POSIX API. This makes it easy to deploy on any POSIX-compatible platform and runs smoothly on various CPU architectures, including x86_64, ARM, MIPS, and RISC-V.

NanoMQ

Official website: https://nanomq.io/

GitHub: https://github.com/nanomq/nanomq

Pros

  • Lightweight design
  • Multi-threading and Async IO
  • Highly portable
  • Small booting footprint
  • Easy to deploy
  • Bridging with brokerless protocols

Cons

  • No clustering support
  • Small community and user base
  • Lack of documentation and tutorials
  • Lack of enterprise features (data Integrations)
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VerneMQ

The VerneMQ project was launched in 2014 and initially developed by Erlio GmbH. The project is licensed under Apache Version 2.0. It supports MQTT versions 3.1, 3.1.1, and 5.0. As the second broker wrote in Erlang/OTP, it borrowed some code from the EMQX project.

Regarding architectural design, VerneMQ is designed to handle millions of concurrent connections and messages with low latency and high throughput. It supports MQTT message persistence in LevelDB and uses a clustering architecture based on the Plumtree library, which implements the Epidemic Broadcast Trees algorithm.

Unfortunately, this Plumtree cluster architecture has not proven to work, even though it seems perfect in theory. The VerneMQ team and community have spent many years trying to make it work, fixing problems such as network split, data inconsistency, and crash recovery.

Finally, the project has stopped being actively developed and maintained, with only about 50 commits in the last 12 months.

Official website: https://www.vernemq.com/

GitHub: https://github.com/vernemq/vernemq

Pros:

  • High availability
  • Horizontal scalability
  • Message persistence

Cons:

  • Not proofed clustering
  • Limited documentation
  • Limited enterprise features
  • Not actively developing

Scalability, Performance, and Reliability

Before we dive into the comparison of features and capabilities of these MQTT brokers, let's review their scalability, availability, performance, latency, and reliability first.

  • Scalability: Can the broker scale horizontally to handle millions of concurrent MQTT connections?
  • Availability: Does the broker support highly available clustering for mission-critical applications?
  • Performance: How many QoS/0/1/2 MQTT messages per second can the broker route and deliver?
  • Latency: How fast can the broker dispatch and deliver an MQTT message from one MQTT client to another?
  • Reliability: Does the broker support MQTT message persistence and delivery without data loss?

Below is a brief analysis of the four MQTT brokers:

EMQX Mosquitto NanoMQ VerneMQ
Scalability
Multi-threading Yes No Yes Yes
Asynchronous I/O Yes Yes Yes Yes
Clustering Yes (over 20 nodes cluster) No No Yes
MQTT connections per node 4M 100k 100k 1M
MQTT connections per cluster 100M N/A N/A ?
Availability
Masterless Clustering Architecture Yes No No Yes
Elastic and Resilient scaling at runtime Yes No No Yes
Auto Clustering Yes No No No
Overload Protection Yes No No Yes
Fault tolerance Yes No No ?
Performance (per node)
QoS0 msgs/sec 2 million 120k 500k ?
QoS1 msgs/sec 800k 80k 400k ?
QoS2 msgs/sec 200k 40k 200k ?
Latency
Latency (varies on different scenarios) Single-digit millisecond latency at scale Up to seconds latency in some scenarios Less than 10 milliseconds in most scenarios Up to seconds latency in some scenarios
Reliability
Message Persistence In RocksDB and External Databases In Files In SQLite In LevelDB
Zero Downtime/Hot Upgrade Yes No No No
Hot Patch Yes No No No

? here means that we were unable to find any publicly available documentation or files that could serve as evidence regarding the item under discussion.

MQTT Protocol and Connectivity

All the presented brokers fully implement MQTT versions 3.1.1 and 5.0 and support MQTT over WebSocket and SSL/TLS encryption. Additionally, EMQX supports MQTT-SN, CoAP, and LwM2M protocol gateways. NanoMQ supports brokerless mode and can work with DDS, ZeroMQ, and Nanomsg.

EMQX and NanoMQ have committed to advancing the MQTT standard. They are pioneers in implementing MQTT over QUIC, the next generation of MQTT protocol that aims to optimize further IoT communication.

EMQX Mosquitto NanoMQ VerneMQ
MQTT 3.1/3.1.1 Yes Yes Yes Yes
MQTT 5.0 Yes Yes Yes Yes
MQTT-SN 1.2 Yes No No No
MQTT over TCP Yes Yes Yes Yes
MQTT over SSL/TLS Yes Yes Yes Yes
MQTT over WebSocket Yes Yes Yes Yes
MQTT over QUIC Yes No Yes No
MQTT Bridging Yes Yes Yes Yes
Shared Subscription Yes Yes Yes Yes
Retained Message Yes Yes Yes Yes
Will Message Yes Yes Yes Yes
MQTT Request/Response Yes Yes Yes Yes
LB (Proxy Protocol) Yes No No Yes
Multi-protocol Gateway Yes No No No
CoAP Yes No No No
LwM2M Yes No No No
DDS Gateway No No Yes No
ZeroMQ Gateway No No Yes No
Nanomsg/NNG No No Yes No

Security, Authentication & Authorization

Security is crucial for connecting IoT devices and data exchanged between connected devices using MQTT brokers. All the compared brokers support secure connections based on TLS/SSL and authentication and authorization mechanisms such as username/password, JWT, X.509 certificates, and access control lists.

Additionally, EMQX offers advanced security features like integration with external databases, OCSP Stapling, fine-grained access control policies, flapping detection, and support for OAuth 2.0 authorization.

EMQX Mosquitto NanoMQ VerneMQ
TLS/SSL Yes Yes Yes Yes
OCSP Stapling Yes Yes No No
Username/Password Authentication Yes Yes Yes Yes
X.509 Certificates Authentication Yes Yes Yes Yes
JWT Authentication Yes Yes (via auth plugin) No ?
LDAP Authentication Yes Yes (via auth plugin) No Yes (via plugin)
Fine-grained Access Control Yes Yes Yes Yes
Authorization using Databases Yes (built-in) Yes (via auth plugins) No Yes (via auth plugins)
Flapping Detection Yes No No No
Audit Logs Yes No No No

Data Integrations (Out-of-the-Box)

All the brokers support integration with external services using REST APIs and WebHook. As lightweight brokers, Mosquitto and NanoMQ do not support data integration. Users can write code to consume MQTT messages from Mosquitto and ingest them into external databases or cloud services.

EMQX implements a built-in SQL-based rule engine to help extract, filter, enrich, and transform MQTT messages in real time within the broker. And the Enterprise Edition of EMQX can seamlessly integrate with Kafka, databases, and cloud services using out-of-the-box data bridges.

EMQX Mosquitto NanoMQ VerneMQ
WebHook Yes Yes Yes Yes
Rule Engine Yes No Yes (limited) No
Message Codec Yes No No No
Schema Registry Yes No No No
Data Bridge Yes No No No
Confluent/Kafka Yes (Enterprise Edition) No No No
SAP Event Mesh Yes (Enterprise Edition) No No No
Apache Pulsar Yes (Enterprise Edition) No No No
RabbitMQ Yes (Enterprise Edition) No No No
MySQL Yes (Enterprise Edition) No No No
PostgreSQL Yes (Enterprise Edition) No No No
SQL Server Yes (Enterprise Edition) No No No
MongoDB Yes (Enterprise Edition) No No No
AWS DynamoDB Yes (Enterprise Edition) No No No
ClickHouse Yes (Enterprise Edition) No No No
InfluxDB Yes (Enterprise Edition) No No No
TimeScaleDB Yes (Enterprise Edition) No No No
Oracle Yes (Enterprise Edition) No No No
Redis Yes (Enterprise Edition) No No No
Cassandra Yes (Enterprise Edition) No No No
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Operability, Observability, and Compatibility

Each broker is user-friendly and equipped with essential logging and debugging features to monitor their status and troubleshoot issues effectively. They can run on various operating systems and public cloud platforms. Besides, EMQX has excellent support for Kubernetes Operator and Terraform.

Additionally, EMQX provides rich visual monitoring capabilities through HTTP API and Dashboard, making it easier to monitor and manage. In addition, EMQX supports integration with Prometheus and Grafana, enabling O&M teams to use third-party monitoring platforms easily.

See: Monitoring MQTT broker with Prometheus and Grafana

EMQX Mosquitto NanoMQ VerneMQ
Dashboard Yes No No No
Configuration HOCON Format Key-value Format HOCON Format Key-value Format
Config Hot update Yes No Yes (Limited) No
REST API Yes Yes Yes Yes
CLI Yes Yes Yes Yes
Remote Console Yes No No Yes
Metrics Yes Yes Yes Yes
Grafana Integration Yes Yes Yes Yes
Prometheus Yes Yes Yes Yes
Docker Yes Yes Yes Yes
Kubernetes Operator Yes (EMQX Kubernetes Operator) No No No
Terraform Yes (EMQX Terraform) No No No

Head-to-Head Comparison Chart

Finally, we summarize an overall evaluation of the top open-source MQTT brokers in the following chart.

EMQX Mosquitto NanoMQ VerneMQ
Scalability Excellent Moderate Good Good
Availability Excellent Moderate Moderate Good
Performance Excellent Excellent Excellent Good
Latency Excellent Good Excellent Good
Reliability Good Good Good Moderate
Security Excellent Excellent Good Good
Authenticaton & Authorization Excellent Good Moderate Good
Connectivity Excellent Good Good Good
Integration Excellent Moderate Moderate Moderate
Operability Good Excellent Good Moderate
Observability Excellent Moderate Moderate Good
Compatibility Good Excellent Excellent Good
Ease of Use Good Excellent Good Good
Community Support Excellent Excellent Good Moderate

Final Thoughts on the Comparison

Over the past decade, open-source MQTT brokers have led the way in innovating MQTT technology. These brokers have played a significant role in advancing the functionality, scalability, and interoperability of the MQTT messaging protocol. Without these contributions, MQTT may not have become as widely adopted and versatile as it is today.

Choosing an MQTT broker depends on various factors, such as the number of connected devices, message throughput, and integration requirements. From the comparison, we can conclude that EMQX is a highly scalable and enterprise-grade broker for large-scale, mission-critical deployments in the cloud. While Mosquitto and NanoMQ are fast and lightweight, making them suitable for deployment on resource-constrained embedded hardware, industrial gateways, and IoT edge servers.

Future Developments

With the rapid expansion of IoT, the number of connected devices is predicted to exceed 100 billion by 2030. As a result, MQTT is poised to become even more indispensable and could potentially serve as the nervous system of the IoT.

Several exciting technological advancements are in the pipeline, including MQTT over QUIC, MQTT Serverless, MQTT Unified Namespace, and more. To learn more about these developments, feel free to check out our blog posts at:

References

[1] 125 billion IoT devices by 2030 says IHS Markit

[2] Comparison of MQTT implementations

[3] A Comparison of MQTT Brokers for Distributed IoT Edge Computing

[4] Open MQTT benchmark suite blog series

[5] 2023 MQTT broker comparison blog series

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