What is MistServer?

MistServer is an open-source MQTT server written in pure ANSI C. It was designed from the ground up to be lightweight, fast, and scalable, ideal for use in IoT devices, embedded systems, and other resource-constrained environments. It is lightweight and has a small memory footprint, making it suitable even for microcontrollers.

Yet despite its small footprint, MistServer provides a full-fledged MQTT 3.1.1 compliant server with all major features including QoS levels, last will and testament, retained messages, persistent sessions, TLS/SSL encryption, web sockets, bridging and clustered nodes. It uses very little CPU and RAM while still achieving high throughput measured in tens of thousands of messages per second.

MistServer is scalable and can handle up to tens of thousands of simultaneous clients when deployed in clustered mode across multiple nodes. This makes it a great fit from small IoT devices all the way up to large enterprise systems. Its authentication features and pluggable architecture provide flexibility to integrate with external authentication providers.

In summary, MistServer delivers high performance, small resource usage, excellent scalability, and an extensible architecture in a tiny package. Its liberal Apache 2 license allows it to be used in commercial products as well. If you need an MQTT server that's fast, lightweight, and highly scalable, MistServer checks all the boxes.

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