NoxMQTT - MQTT Client for Embedded Devices

NoxMQTT is a complete MQTT client that's cross platform and enables optimized simple access to MQTT brokers.

License

NoxMQTT is dual-licensed under:

• GPL-2.0-only
• LicenseRef-Argenox-Commercial

You may use NoxMQTT under GPL v2.0 only, or under a separate commercial license from Argenox Technologies LLC. See LICENSE.

Why another MQTT Client?

While there's are several mqtt clients out there, these clients tend to be relatively large and complicated to integrate in a real embedded system.

NoxMQTT is small, efficient, and most importantly easy to use.

Our experience with other MQTT clients is that they hide a lot of things behind the scenes which makes them difficult to use in real products where errors can occur for a variety of reasons.

Many of these clients are also vendor/platform specific, making reusing of code difficult. Some of these have terrible code, wierd behaviors and side effects that make creating a reliable

Integrating NoxMQTT

• Add files in src/lib to your project

• Import header files #include "noxmqtt.h" #include "noxmqtt_tal.h"

• Use an existing TCP Abstraction Layer (TAL) file or create your own. This file provides standard TCP socket connectivity functions. See noxmqtt_tal.h for files needed.

• Call library functions

CMake Builds

The core noxmqtt library target is transport-agnostic and does not depend on NoxTLS.

Build the cross-platform noxmqtt CLI with plain TCP transport:

cmake -S . -B build -DNOXMQTT_BUILD_CLI_APP=ON
cmake --build build

Build the noxmqtt CLI with a NoxTLS-backed secure transport without adding NoxTLS to the noxmqtt library target:

cmake -S . -B build-noxtls \
  -DNOXMQTT_BUILD_CLI_APP=ON \
  -DNOXMQTT_CLI_ENABLE_NOXTLS=ON \
  -DNOXMQTT_NOXTLS_ROOT=/path/to/noxtls \
  -DNOXMQTT_NOXTLS_PROFILE=default
cmake --build build-noxtls

Relevant CMake options:

• NOXMQTT_BUILD_CLI_APP: builds the noxmqtt command-line application.
• NOXMQTT_CLI_ENABLE_NOXTLS: enables the CLI application's NoxTLS transport.
• NOXMQTT_BUILD_NOXTLS_TRANSPORT: builds the reusable noxmqtt_transport_noxtls module even when the CLI app is not using it.
• NOXMQTT_NOXTLS_ROOT: points at the NoxTLS source tree used by the reusable NoxTLS transport module.
• NOXMQTT_NOXTLS_PROFILE: selects the NoxTLS feature profile for secure CLI builds.

Reusable transport targets:

• noxmqtt_transport_windows_tcp: reusable Windows TCP transport module.
• noxmqtt_transport_posix_tcp: reusable POSIX TCP transport module for Linux and macOS.
• noxmqtt_transport_noxtls: reusable secure transport module backed by NoxTLS on the active host platform.

CLI Application

The repository now ships a full client application named noxmqtt.

Examples:

noxmqtt pub -h broker.example.com -p 1883 -t demo/topic -m hello -q 1
noxmqtt sub --tls --cafile ./ca.pem -h broker.example.com -p 8883 -t demo/topic --count 1
noxmqtt interactive --host test.mosquitto.org --port 1883

noxmqtt interactive opens a REPL with connect, disconnect, publish, subscribe, unsubscribe, and live configuration commands. The binary also supports one-shot pub, sub, and unsub modes so it can be used similarly to the Mosquitto CLI tools.

ESP-IDF Component

This repository includes an ESP-IDF component definition at the repository root for publishing argenox/noxmqtt to the ESP Component Registry.

Example dependency:

dependencies:
  argenox/noxmqtt: "^1.0.0"

The published root component is now MQTT-core only. It packages the protocol sources from src/noxmqtt-lib and does not bundle any ESP-IDF socket or TLS transport implementation.

For ESP-IDF applications, pick exactly one local transport component from port/esp_idf/README.md:

• noxmqtt_transport_espidf_tcp
• noxmqtt_transport_espidf_noxtls

Example app configuration with the local NoxTLS transport:

list(APPEND EXTRA_COMPONENT_DIRS
    "/path/to/noxmqtt/port/esp_idf/components"
    "/path/to/noxtls/ports/esp-idf"
)

idf_component_register(
    SRCS "main.c"
    REQUIRES
        noxmqtt
        noxmqtt_transport_espidf_noxtls
)

That keeps noxmqtt transport-agnostic while allowing the application to opt into MQTTS by adding the NoxTLS-backed transport component.

Publishing on tag release

GitHub Actions publishes the component on tag pushes via .github/workflows/publish-esp-idf-component.yml.

Before the workflow can upload with OIDC, configure argenox/noxmqtt in the ESP Component Registry and add this repository/workflow as a trusted uploader.