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Open Source Real-Time Operating Systems

Discover the best Open Source RTOS solutions for embedded systems and IoT devices

Featured Projects

ESP32 Mesh Control

An ESP-IDF based firmware for creating local mesh networks using ESP32-DevKitV1 hardware. It features a self-hosted web server for configuration, real-time topology visualization via WebSockets, and a custom OTA update mechanism that broadcasts firmware to all nodes in the mesh.

freertos lwipspiffs

Riden Dongle

An alternative firmware for Riden WiFi modules that provides Modbus TCP and SCPI support for RD-series power supplies. Built using the Arduino framework for ESP8266, it enables integration with professional lab automation tools and provides a comprehensive web interface for remote monitoring and control.

lwip

TISM - The Incredible State Machine

TISM is a cooperative multitasking framework for the Raspberry Pi Pico (RP2040 and RP2350) that enables concurrent task execution through a state-machine architecture. It provides essential system services including dual-core scheduling, a thread-safe messaging system, and hardware abstraction for interrupts and timers.

Cydintosh

Cydintosh is a Macintosh Plus emulator designed for the ESP32-based Cheap-Yellow-Display (CYD). It utilizes the Musashi 68k emulator core and umac to run classic Macintosh software alongside modern ESP32 features like WiFi, MQTT, and Home Assistant integration.

freertos littlefslwip

Zephyr RTOS AI Harness

A specialized harness designed for AI-assisted embedded firmware development using the Zephyr RTOS. It provides a comprehensive set of 'Agent Skills' covering core Zephyr subsystems like BLE, device drivers, and kernel primitives to help AI agents generate, understand, and manage firmware code efficiently.

zephyr littlefs

RP2040/RP2350 ADC Non-linearity Correction

This project provides software-based tools and algorithms to correct the ADC non-linearity issues in RP2040 and RP2350 microcontrollers, specifically addressing the RP2040-E11 errata. It includes measurement firmware, Python scripts for data analysis, and general-purpose or device-specific calibration code for C++ and Python environments.

La Marzocco Round Controller

A standalone ESP32-S3 firmware project for a custom round external controller for La Marzocco espresso machines. It utilizes the ESP-IDF framework, FreeRTOS, and the LVGL graphics library to provide an on-device UI, BLE/cloud connectivity, and a local setup portal for managing machine settings and recipes.

freertos lvglnimblelwip

STM32F103 Quadruped Robot

A sophisticated quadruped crawling robot powered by an STM32F103C8T6 microcontroller and an ESP32-CAM for real-time vision and remote connectivity. It utilizes FreeRTOS for multi-tasking and MicroPython for the wireless communication stack, supporting both cloud-based MQTT control via a mobile app and local control through a web interface.

freertos micropython

Latest RTOS

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contiki-ng

release/v5.1

Contiki-NG is an open-source, cross-platform operating system designed for next-generation IoT devices, focusing on dependable, low-power communication. It provides a full, RFC-compliant IPv6 networking stack and supports modern industrial standards such as 6LoWPAN, 6TiSCH, RPL, and CoAP for resource-constrained hardware.

1,486 Updated: 5/5/2026

ARM Cortex-M3ARM Cortex-M4ARM Cortex-M33MSP430NativeSimulatorRenodePOSIX +7 more

BSD 3-Clause

embox

v0.7.1

Embox is a highly modular and configurable real-time operating system designed to execute Linux-compatible software on resource-constrained embedded systems and microcontrollers. It provides a POSIX-compliant environment, allowing developers to port complex desktop-grade libraries and applications like Qt, OpenCV, and PJSIP to platforms with limited RAM and ROM.

1,560 Updated: 5/5/2026

ARMARM Cortex-MARM Cortex-Ax86RISC-VMIPSSPARCPowerPC +8 more

BSD

Hubris

all-sp-v1.0.67

Hubris is a memory-isolated, task-based RTOS written in Rust, specifically designed for deeply-embedded microcontrollers with high reliability requirements. It eliminates dynamic resource allocation and runtime task creation to minimize attack surfaces and ensure deterministic behavior in critical systems.

3,497 Updated: 5/5/2026

ARMARM Cortex-MLinuxWindowsmacOSPOSIX

MPL-2.0

RIOT

2026.01

RIOT is a modular, open-source real-time operating system specifically engineered for the Internet of Things (IoT), supporting a wide range of 8-bit, 16-bit, and 32-bit microcontrollers. It features a micro-kernel architecture with a preemptive, tickless scheduler and provides a uniform API with partial POSIX compliance to simplify cross-platform development and code reuse.

5,718 Updated: 5/5/2026

ARMARM Cortex-MARM7RISC-VXtensaAVRMSP430Linux +7 more

LGPL-2.1

Tock

release-2.2

Tock is a secure, concurrent embedded operating system designed for ARM Cortex-M and RISC-V microcontrollers, prioritizing isolation between the kernel, device drivers, and applications. It leverages Rust's memory safety for its kernel and hardware Memory Protection Units (MPUs) to run multiple mutually distrustful applications on resource-constrained hardware with as little as 64kB of RAM.

6,298 Updated: 5/5/2026

ARM Cortex-MRISC-VQEMU

Apache-2.0MIT

NuttX

nuttx-12.13.0

Apache NuttX is a highly scalable, standards-compliant real-time operating system (RTOS) designed for deeply embedded environments ranging from 8-bit to 64-bit architectures. It distinguishes itself by strictly adhering to POSIX and ANSI standards, providing a familiar Unix-like programming interface while maintaining a minimal footprint and modular architecture.

3,837 Updated: 5/4/2026

ARMARM Cortex-MARM Cortex-AARM Cortex-RARM7ARM9AArch32AArch64 +22 more

Apache-2.0

Phoenix-RTOS

v3.3.2

Phoenix-RTOS is an open-source, microkernel-based, realtime operating system for resource constrained devices.

157 Updated: 5/4/2026

ARMx86RISC-V

BSD

RT-Thread

v5.2.2

RT-Thread is a modular, object-oriented real-time operating system (RTOS) designed for both resource-constrained microcontrollers and high-performance IoT devices. It provides a scalable architecture ranging from a 3KB footprint kernel to a comprehensive IoT OS featuring a vast ecosystem of over 450 software packages and standardized interfaces like POSIX and CMSIS.

11,946 Updated: 5/4/2026

ARMARM Cortex-MARM Cortex-RARM Cortex-AARM7ARM9ARM11RISC-V +10 more

Apache-2.0

Latest Libraries

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Tensorflow Micro

v2.21.0

TensorFlow is an end-to-end open-source platform for machine learning that provides a comprehensive ecosystem of tools, libraries, and community resources for both research and production. It features a flexible architecture allowing for seamless deployment across diverse hardware including CPUs, GPUs, and TPUs, while offering stable APIs in Python and C++ alongside a rich set of specialized extensions.

195,007 Updated: 5/6/2026

Apache-2.0

MachineLearning

LVGL

v9.5.0

LVGL is a lightweight, open-source C graphics library designed to build professional user interfaces on any microcontroller or microprocessor. It features a hardware-independent architecture with low memory requirements, supporting advanced rendering features like anti-aliasing, animations, and complex layout engines.

23,461 Updated: 5/5/2026

MIT

GUI

Nuklear

v4.13.3

Nuklear is a portable, single-header immediate-mode graphical user interface toolkit written in ANSI C (C89). It is designed as a dependency-free, embeddable UI library that provides a modular approach, outputting primitive draw commands or vertex buffers rather than abstracting platform-specific rendering backends.

11,105 Updated: 5/5/2026

MIT

GUI

Open Thread

thread-reference-20250612

OpenThread is an open-source, OS-agnostic implementation of the Thread networking protocol designed for low-power wireless mesh networking in home and commercial automation. It features a highly portable architecture with a narrow platform abstraction layer, supporting System-on-Chip (SoC), Network Co-Processor (NCP), and Radio Co-Processor (RCP) designs while maintaining a small memory footprint.

3,932 Updated: 5/5/2026

BSD 3-Clause

Wireless

sqlite

vesion-3.45.1

SQLite is a C-language library that implements a small, fast, self-contained, high-reliability, and full-featured SQL database engine. It functions as a serverless, zero-configuration database that compiles SQL statements into bytecode for execution on a custom virtual machine, making it the most widely deployed database engine in the world.

9,538 Updated: 5/5/2026

Public Domain

Database

libwebsockets

valgrind-clean

Libwebsockets (LWS) is a lightweight, high-performance C networking library providing client and server implementations for HTTP/1, HTTP/2, WebSockets, MQTT, and other protocols. It is designed for high scalability and flexibility, supporting both resource-constrained embedded RTOS environments like ESP32 and mass cloud serving through a non-blocking, event-driven architecture.

5,265 Updated: 5/5/2026

MIT

Network

AWTK = Toolkit AnyWhere

AWTK (Toolkit AnyWhere) is a high-performance, cross-platform GUI engine designed for a wide range of devices from low-end Cortex-M3 microcontrollers to high-end desktop and mobile systems. It features a decoupled MVVM architecture, hardware acceleration support, and a comprehensive suite of tools including a visual UI designer and multi-language bindings.

3,292 Updated: 5/4/2026

LGPLLGPL-2.1

GUI

Modbus-STM32-HAL-FreeRTOS

This library provides a comprehensive Modbus implementation for STM32 microcontrollers, supporting TCP, RTU (USART), and USB-CDC interfaces. Built upon the STM32 Cube HAL and FreeRTOS, it enables multithread-safe concurrent execution of multiple Modbus Master and Slave instances across various hardware transport layers.

764 Updated: 4/30/2026

LGPL-2.1

Middleware