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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

PatternFlow

PatternFlow is an open-source LED synthesizer built on the ESP32-S3 platform, designed to drive HUB75 RGB LED matrices with real-time, interactive visuals. The system features a modular C++ firmware architecture, four physical rotary encoders for tactile control, and a web-based ecosystem for pattern generation and audio-reactive synchronization.

Obscura One

Obscura One is an open-source, screenless digital camera based on the ESP32-CAM platform and housed in a 3D-printable enclosure. It captures JPEG images to a Micro SD card and features a minimalist single-button control scheme with haptic feedback and a Wi-Fi access point for wireless photo retrieval.

RNode Firmware — NeoPixel Edition

This project is a specialized fork of the RNode Firmware Community Edition (CE) that introduces NeoPixel status indicators for ESP32-based hardware, specifically the LilyGO LoRa32 v2.1. It serves as a software-defined LoRa modem for the Reticulum network stack, providing visual feedback for boot sequences and data transmission using the ESP32's underlying FreeRTOS-based Arduino core and SPIFFS for asset management.

freertos spiffs

Temperature-Controlled Ventilation System for Indoor Environments

An STM32F103R6-based embedded system that provides automated and manual ventilation control based on real-time temperature monitoring. It utilizes an LM35 sensor, PWM for fan speed regulation, and an L298N H-bridge for direction control, with status updates displayed on an LCD1602. The project demonstrates peripheral integration using the STM32 HAL for ADC, timers, and external interrupts.

ESP32 RTSP Microphone for BirdNET

A high-performance network microphone firmware for Seeed Studio XIAO ESP32 boards that streams 16-bit PCM audio via RTSP. It is designed for integration with BirdNET-Go and BirdNET-Pi for automated bird sound identification and includes a Web UI, MQTT telemetry, and OTA support.

freertos lwip

Claude Pocket

Claude Pocket is a voice-activated AI assistant firmware for the M5Stack Cardputer ADV, powered by Anthropic's Claude and OpenAI's Whisper and TTS APIs. It features a custom C++ implementation that handles voice activity detection, streaming transcription, and real-time audio playback on hardware without external PSRAM.

freertos littlefsplatformio-platformio-core

esp-nus — High-throughput BLE 5 UART bridge

A transparent UART-to-BLE cable replacement for the ESP32-C6 that implements the Nordic UART Service (NUS). It is specifically optimized for high throughput using BLE 5 features like LE 2M PHY, Data Length Extension (DLE), and credit-based flow control.

freertos nimble

OttoClaw

OttoClaw is an AI-powered desktop humanoid robot system built on the ESP32-S3 and FreeRTOS. It features a local lightweight agent that handles conversation, memory, and autonomous physical movements through six servos without relying on cloud servers, utilizing LVGL for its graphical interface and SPIFFS for local data persistence.

freertos lvglspiffslwip

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.

1,503 Updated: 6/25/2026

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.

1,568 Updated: 6/25/2026

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

BSD

Hubris

oxide-rot-1-v1.39.0

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.

3,548 Updated: 6/25/2026

ARMARM Cortex-MLinuxWindowsmacOSPOSIX

MPL-2.0

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.

12,065 Updated: 6/25/2026

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

Apache-2.0

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.

6,360 Updated: 6/25/2026

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.

3,916 Updated: 6/24/2026

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

Apache-2.0

RIOT

2026.04.01

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.

5,759 Updated: 6/24/2026

ARMARM Cortex-MARM7RISC-VXtensaAVRMSP430Linux +7 more

LGPL-2.1

FreeRTOS

202411.00

FreeRTOS is a market-leading real-time operating system kernel designed for microcontrollers and small microprocessors, featuring a small memory footprint and fast execution times. It provides a comprehensive ecosystem of libraries for IoT connectivity, security, and over-the-air updates, supporting over 40 processor architectures including ARM and RISC-V.

7,503 Updated: 6/19/2026

ARMARM Cortex-MARM Cortex-AARM Cortex-RARM7ARM9ARM11RISC-V +28 more

MIT

Latest Libraries

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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.

3,295 Updated: 6/26/2026

LGPLLGPL-2.1

GUI

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.

195,909 Updated: 6/26/2026

Apache-2.0

MachineLearning

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.

797 Updated: 6/25/2026

LGPL-2.1

Middleware

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.

23,905 Updated: 6/25/2026

MIT

GUI

Open Thread

v2026.06.0

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.

3,969 Updated: 6/25/2026

BSD 3-Clause

Wireless

OpenBLT Bootloader

openblt_v012101

OpenBLT is a highly customizable, open-source bootloader designed for 8-bit, 16-bit, and 32-bit microcontrollers to facilitate firmware updates without specialized debugger hardware. It utilizes the standardized ASAM MCD-1 XCP protocol for communication and supports a wide range of interfaces including CAN, RS232, USB, and TCP/IP, complemented by cross-platform host utilities for Windows and Linux.

939 Updated: 6/25/2026

GPL-3.0

Bootloader

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.

9,906 Updated: 6/25/2026

Public Domain

Database

NimBLE

nimble_1_9_0_tag

Apache NimBLE is a feature-complete, open-source Bluetooth Low Energy (BLE) 5.4 stack comprising both Host and Controller layers. Designed for resource-constrained embedded systems, it serves as a portable alternative to proprietary stacks, supporting advanced features like Bluetooth Mesh, multi-role concurrency, and high-density connection management.

875 Updated: 6/24/2026

Apache-2.0

Wireless