How to load test MQTT applications with Gatling

MQTT is the go-to protocol for real-time, lightweight communication across millions of devices. From smart homes to industrial IoT, MQTT powers systems where low latency and reliability are non-negotiable.

But here’s the catch: when your app scales, performance bottlenecks often surface where you least expect them—impacting both device-to-cloud communication and user experience.

So how do you make sure your MQTT infrastructure performs at scale?

MQTT protocols need specialized testing

Most load testing tools are built for HTTP APIs and traditional web traffic. MQTT, being a stateful, event-driven protocol, behaves differently:

• Persistent connections must be handled across thousands of clients
• Topic-based message distribution adds architectural complexity
• QoS levels, retained messages, and will messages introduce variables that impact performance

Without a purpose-built approach to MQTT load testing, teams are often left guessing:

• Can our broker handle thousands of concurrent connections?
• Will latency spike under high throughput?
• Are messages reliably delivered under stress?

Unfortunately, these questions are usually answered too late—in production.

Avoiding downtime in IoT, messaging, and Edge applications

Whether you’re building connected devices, live chat, or telemetry platforms, MQTT performance directly affects:

• Device responsiveness and uptime
• Data accuracy and loss prevention
• Customer experience and SLA compliance

Testing MQTT systems at scale isn’t just about robustness—it’s about reliability, cost efficiency, and avoiding production failures in high-stakes environments.

Companies that skip performance testing for MQTT often end up over-provisioning infrastructure or, worse, firefighting stability issues during customer-facing events.

Gatling + MQTT plugin

Gatling is widely known for its powerful load testing engine and test-as-code flexibility. With the MQTT plugin, teams can now simulate thousands of real-time MQTT clients—publishing, subscribing, and managing connections—at scale.

Follow our full tutorial to start building and running MQTT tests with Gatling:

🔗 Read the full guide →