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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 Virtual Cat Project

An interactive virtual pet built with Rust on the ESP32-C3, featuring environmental sensing and a state-driven animation system. It utilizes DHT and LDR sensors for environmental awareness and NVS for persistent statistics.

freertos

E-ink Meeting Room Schedule Display

A wireless e-ink device based on the ESP32-powered Soldered Inkplate 6 platform that displays meeting room schedules. It utilizes the Roombelt backend for data and features a secondary digital photo frame mode that reads images from a microSD card.

freertos

Toyota RAV4 Climate Control Panel LIN Bus Interface

This project provides an STM32 HAL-based implementation for communicating with a Toyota RAV4 climate control panel via the LIN bus. Targeting the STM32G474RE microcontroller, it demonstrates reverse engineering techniques for automotive HMI modules and utilizes DMA for efficient serial data handling.

cmsis

RP2040 DAC-Amp

An experimental USB DAC and Class-D amplifier implemented on the Raspberry Pi RP2040. The project uses PIO-based H-bridge control and a 4th-order delta-sigma modulator to drive external MOSFETs directly from the microcontroller.

Flexispot Web Controller

This project enables remote control and monitoring of Flexispot standing desks using an Arduino Nesso N1 or other M5Unified-compatible ESP32 devices. It emulates the original desk controller by communicating with the LoctekMotion control box via serial protocols, providing both a web-based UI and physical button controls.

freertos

IkeDryBox - Smart 3D Filament Dryer

IkeDryBox is an advanced ESP32-based DIY filament dryer featuring precision PID temperature control and a responsive LVGL touch interface. It integrates seamlessly with Home Assistant via MQTT and provides a built-in WebUI for real-time parameter tuning and network configuration.

lvgl

pico_fft: FFT Library for Raspberry Pi Pico

A lightweight and efficient wrapper for the KISS FFT library, specifically designed for the Raspberry Pi Pico (RP2040). It provides high-level functions for capturing analog signals via ADC and DMA, processing them into frequency bins, and performing real-time signal analysis.

M5Paper Buddy

A physical companion device for the Claude Code AI assistant, utilizing the M5Paper V1.1 e-ink display. It features real-time session mirroring, hardware-based tool approval, and touch-screen interactions powered by ESP32 and a Python-based daemon.

freertos littlefsplatformio-platformio-core

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