Mongoose is a full-stack embedded networking library for C/C++. It provides TCP/IP stack with drivers, TLS 1.3, HTTP, WebSocket, MQTT, and firmware OTA updates in just two files: mongoose.c and mongoose.h. It runs on STM32, NXP i.MX RT, and other microcontrollers, on bare metal or with an RTOS.

Mongoose is ideal for implementing TCP/IP cloud connectivity, device web dashboards, firmware updates, and remote control. It is self-contained and has no external dependencies.

Use it instead of lwIP + mbedTLS + httpd + an MQTT client + OTA glue code, or run it on top of lwIP or Zephyr.

On the market since 2004, used by a vast number of open source and commercial products - it even runs on the International Space Station! Features include:

• Cross-platform:
  • works on Linux/UNIX, MacOS, Windows, Android, STM32, NXP, ESP32, Nordic, TI, Microchip, Infineon, Renesas and other chips
  • write code once - and it'll work everywhere
  • ideal for the unification of the network infrastructure code across company
• Built-in protocols: plain TCP/UDP, SNTP, HTTP, MQTT, Websocket, Modbus-TCP, and other
• Asynchronous DNS resolver
• Tiny static and run-time footprint
• Source code is both ISO C and ISO C++ compliant
• Very easy to integrate
• Own TCP/IP stack for bare metal / RTOS, or run on top of any existing one (lwIP, Zephyr, ...)
• Built-in TLS 1.3 stack. Also can use external TLS libraries - mbedTLS, OpenSSL, or other
• Does not depend on any other software to implement networking
• Built-in firmware updates for STM32 H5, STM32 H7, NXP IMXRT, RP2040/2350, ESP32 and more
• Commercial support with proactive security updates; CRA-compliant

Mongoose is ideal for IoT devices, embedded web servers, OTA updates, MQTT telemetry, secure device dashboards, REST APIs on microcontrollers

See https://mongoose.ws/ for complete documentation, videos, case studies, etc.

Mongoose has its own built-in TCP/IP stack with drivers, so it needs no additional software to implement networking. The built-in stack runs on bare metal and under any RTOS. Platforms supported by the Mongoose built-in TCP/IP stack:

Mongoose can also run on top of any TCP/IP stack that supports the BSD sockets API. Platforms supported via 3rd party TCP/IP stacks:

Below are quick snippets that should give an idea how simple the API is and how easy it is to create applications with it.

Create a simple web server that serves a directory. The behavior of the HTTP server is specified by its event handler function:

#include "mongoose.h"   // To build, run: cc main.c mongoose.c

// HTTP server event handler function
void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_HTTP_MSG) {
    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
    struct mg_http_serve_opts opts = { .root_dir = "./web_root/" };
    mg_http_serve_dir(c, hm, &opts);
  }
}

int main(void) {
  struct mg_mgr mgr;  // Declare event manager
  mg_mgr_init(&mgr);  // Initialise event manager
  mg_http_listen(&mgr, "http://0.0.0.0:8000", ev_handler, NULL);  // Setup listener
  for (;;) {          // Run an infinite event loop
    mg_mgr_poll(&mgr, 1000);
  }
  return 0;
}

HTTP server implements a REST API that returns current time. JSON formatting:

static void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_HTTP_MSG) {
    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
    if (mg_match(hm->uri, mg_str("/api/time/get"), NULL)) {
      mg_http_reply(c, 200, "", "{%m:%lu}\n", MG_ESC("time"), time(NULL));
    } else {
      mg_http_reply(c, 500, "", "{%m:%m}\n", MG_ESC("error"), MG_ESC("Unsupported URI")); 
    }
  }
}

MQTT client that subscribes to a topic device1/rx and echoes incoming messages to device1/tx:

#include "mongoose.h"

static const char *s_mqtt_url = "mqtt://broker.hivemq.com:1883";
static struct mg_connection *s_mqtt_conn = NULL;

// MQTT connection event handler function
static void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_OPEN) {
    MG_INFO(("%lu created, connecting to %s ...", c->id, s_mqtt_url));
  } else if (ev == MG_EV_MQTT_OPEN) {
    struct mg_mqtt_opts opts = {.qos = 1, .topic = mg_str("device1/rx")};
    mg_mqtt_sub(c, &opts);
    MG_INFO(("%lu connected, subscribing to %s", c->id, opts.topic.buf));
  } else if (ev == MG_EV_MQTT_MSG) {
    char response[100];
    struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
    struct mg_mqtt_opts opts = {.qos = 1, .topic = mg_str("device1/tx")};
    mg_snprintf(response, sizeof(response), "Received [%.*s] / [%.*s]",
                mm->topic.len, mm->topic.buf, mm->data.len, mm->data.buf);
    opts.message = mg_str(response);
    mg_mqtt_pub(c, &opts);
  } else if (ev == MG_EV_CLOSE) {
    MG_INFO(("%u closing", c->id));
    s_mqtt_conn = NULL;
  }
}

// Reconnection timer function. If we get disconnected, reconnect again
static void timer_fn(void *arg) {
  struct mg_mgr *mgr = (struct mg_mgr *) arg;
  if (s_mqtt_conn == NULL) {
    struct mg_mqtt_opts opts = {.clean = true};
    s_mqtt_conn = mg_mqtt_connect(mgr, s_mqtt_url, &opts, ev_handler, NULL);
  }
}

int main() {
  struct mg_mgr mgr;  // Mongoose event manager. Holds all connections
  mg_mgr_init(&mgr);  // Initialise event manager
  mg_timer_add(&mgr, 3000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, timer_fn, &mgr);
  for (;;) {
    mg_mgr_poll(&mgr, 1000);  // Infinite event loop
  }
  return 0;
}

Mongoose is dual-licensed:

• GPLv2: free for open source projects. Many popular open source projects use Mongoose, for example SWUpdate, the embedded Linux update framework
• Commercial: for closed-source products. Includes support directly from the engineers who wrote the whole stack, and early security fixes. See licensing

• Mongoose is used by hundreds of businesses, from Fortune500 giants like Siemens, Schneider Electric, Broadcom, Bosch, Google, Samsung, Qualcomm, Caterpillar to the small businesses
• Used to solve a wide range of business needs, like implementing Web UI interface on devices, RESTful API services, telemetry data exchange, remote control for a product, remote software updates, remote monitoring, and others
• Deployed to hundreds of millions devices in production environment worldwide
• See Case Studies from our respected customers like Schneider Electric (industrial automation), Broadcom (semiconductors), Pilz (industrial automation), and others
• See Testimonials from engineers that integrated Mongoose in their commercial products
• We provide Evaluation and Commercial licensing, support, consultancy and integration services - don't hesitate to contact us

We take security seriously:

1. Mongoose repository runs a continuous integration test powered by GitHub, which runs through hundreds of unit tests on every commit to the repository. Our unit tests are built with modern address sanitizer technologies, which help to find security vulnerabilities early
2. Mongoose repository is integrated into Google's oss-fuzz continuous fuzzer which scans for potential vulnerabilities continuously
3. We receive periodic vulnerability reports from the independent security groups like Cisco Talos, Microsoft Security Response Center, MITRE Corporation, Compass Security and others. In case of the vulnerability found, we act according to the industry best practice: hold on to the publication, fix the software and notify all our customers that have an appropriate subscription
4. Some of our customers (for example NASA) have specific security requirements and run independent security audits, of which we get notified and in case of any issue, act similar to (3).

Please report via https://github.com/cesanta/mongoose/security/advisories. Do NOT create a github issue.

Technical guides and deep dives into embedded web servers, WebUI integration and embedded networking technologies:

• Embedded Web Server: A Comprehensive Guide for Modern Connected Devices
• Building Embedded Web Device Dashboards
• ESP32 Device Dashboard: A Step-by-Step Guide for Developers
• How to build an STM32 Web Dashboard
• STM32 WebSocket Guide
• Web File Manager on STM32, ESP32 and Embedded Linux
• Web dashboard on Zephyr RTOS
• Limiting TCP/IP RAM usage on STM32
• STM32 Ethernet explained
• MQTT on a Microcontroller
• STM32 OTA Firmware Update
• RP2350 OTA Firmware Update
• STM32 Ethernet and caches
• NXP RW612 OTA Firmware Update
• lwIP vs Mongoose - TCP/IP Stack Integration Benchmark
• Embedded TCP/IP Stacks Comparison
• STM32H5 File System on Internal Flash: LittleFS + Mongoose
• Firmware OTA and remote control on NXP FRDM-RW612
• 25000 WebSocket messages per second on STM32 Nucleo-H723ZG
• How to connect STM32 to AWS IoT Core
• How to connect STM32 to Azure IoT Hub
• How to connect STM32 to EMQX
• STM32 Device Management deep dive: Secure OTA, Remote Control, health monitor
• STM32 TCP/IP footprint: how much flash and RAM does Mongoose take?

Contributions are welcome! Please follow the guidelines below:

• Sign Cesanta CLA and send GitHub pull request
• Make sure that PRs have only one commit, and deal with one issue only