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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

Sesame Robot Micro

A compact robotics platform featuring firmware for motor control and a Wi-Fi bridge. It utilizes an ESP32-C6 for wireless connectivity and a main board for servo-driven animations and OLED face rendering. The project supports various motion sequences, captive portal control, and optional BLE gamepad integration.

CYD ANSI-VT100 Serial Terminal

A mini-project that transforms the ESP32-based Cheap Yellow Display (CYD) into a standalone ANSI-VT100 serial terminal. It utilizes the FabGL library to handle terminal emulation and display output, allowing users to monitor serial data from other microcontrollers at 115200 baud without a PC.

freertos

EV2400 Reimplementation for Raspberry Pi Pico

A Rust-based reimplementation of the Texas Instruments EV2400 hardware interface using the Raspberry Pi Pico (RP2040). It enables communication with TI battery gauge ICs via I2C and GPIO using the Embassy async framework, allowing the Pico to act as a bridge for TI's Battery Management Studio.

flexPTP

A lightweight IEEE 1588 Precision Time Protocol (PTP) implementation optimized for resource-constrained microcontrollers. It supports both master and slave configurations, multiple transport mechanisms, and advanced clock servos like PID and Kalman filters. The library targets ARM Cortex-M platforms and integrates with lwIP or EtherLib network stacks to achieve sub-100ns synchronization precision.

freertos lwip

S/PDIF Recorder for Raspberry Pi Pico

A high-resolution digital audio recorder that captures S/PDIF signals and stores them as WAV files on microSD media. It supports up to 24-bit/192kHz sampling and is compatible with Raspberry Pi Pico (RP2040) and Pico 2 (RP2350) microcontrollers.

lwip

ZephyrWatch

An open-source smartwatch firmware built on the Zephyr RTOS and LVGL graphics library. It targets the ESP32-S3-Touch-LCD-1.28 hardware, featuring BLE time synchronization, device information services, and a real-time counter for time tracking.

zephyr lvgl

ESP32 Cheap Yellow Display MicroPython LVGL

A comprehensive resource for running MicroPython and LVGL on the ESP32-2432S028R 'Cheap Yellow Display'. It provides precompiled firmwares for LVGL9 and LVGL8, specialized drivers for ILI9341 and XPT2046, and detailed guides for display calibration and UI development.

freertos lvglmicropython

ESP32 Jarolift Controller

A comprehensive firmware for ESP32 microcontrollers to control Jarolift TDEF 433MHz radio shutters via a CC1101 transceiver. It provides a mobile-friendly WebUI, MQTT integration for smart home systems like Home Assistant, and advanced timer functions including sunrise and sunset triggers.

freertos spiffslwip

Latest RTOS

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ChibiOS/RT

ver21.11.4

ChibiOS is a modular, high-performance development environment for embedded systems, featuring a dual-kernel architecture with the full-featured RT kernel and the ultra-compact NIL kernel. It provides a comprehensive Hardware Abstraction Layer (HAL), a Virtual File System (VFS), and advanced sandboxing capabilities, making it highly suitable for functional safety and multicore ARM Cortex-M applications.

833 Updated: 3/22/2026

ARMARM Cortex-MARM Cortex-AARM Cortex-RARM7ARM9ARM11POSIX

GPL-3.0

NuttX

nuttx-12.12.0

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.

3,751 Updated: 3/22/2026

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

Apache-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.

11,853 Updated: 3/22/2026

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

Apache-2.0

embox

v0.7.0

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.

1,554 Updated: 3/21/2026

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

BSD

Hubris

all-sp-v1.0.65

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.

3,463 Updated: 3/21/2026

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.

5,701 Updated: 3/21/2026

ARMARM Cortex-MARM7RISC-VXtensaAVRMSP430Linux +7 more

LGPL-2.1

Zephyr

v4.3.0

Zephyr is a scalable, security-focused real-time operating system (RTOS) designed for resource-constrained devices across multiple hardware architectures. It features a modular, small-footprint kernel with an extensive suite of subsystems, including a native networking stack, comprehensive Bluetooth Low Energy support, and a robust device driver model.

14,763 Updated: 3/21/2026

ARMARM Cortex-MARM Cortex-RARM Cortex-AAArch32AArch64RISC-VXtensa +20 more

Apache-2.0

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.

1,480 Updated: 3/20/2026

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

BSD 3-Clause

Latest Libraries

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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.

3,916 Updated: 3/22/2026

BSD 3-Clause

Wireless

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.

3,293 Updated: 3/21/2026

LGPLLGPL-2.1

GUI

FlashDB

2.1.1

FlashDB is an ultra-lightweight, high-performance embedded database optimized for Flash memory, supporting both Key-Value (KVDB) and Time Series (TSDB) data models. It is designed to minimize resource consumption with near-zero RAM usage while ensuring data reliability through power-off protection and extending hardware lifespan via wear leveling.

2,487 Updated: 3/21/2026

Apache-2.0

Database

esp-nimble-cpp

2.4.0

esp-nimble-cpp is a high-performance, thread-safe C++ wrapper for the Apache NimBLE Bluetooth Low Energy stack, specifically optimized for the ESP32 series. It provides a resource-efficient alternative to the default Bluedroid-based library, significantly reducing RAM and Flash consumption while maintaining API compatibility with popular ESP32 BLE libraries.

270 Updated: 3/21/2026

Apache-2.0

Wireless

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.

23,040 Updated: 3/21/2026

MIT

GUI

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.

9,235 Updated: 3/21/2026

Public Domain

Database

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.

194,309 Updated: 3/21/2026

Apache-2.0

MachineLearning

Nuklear

4.13.2

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.

10,964 Updated: 3/20/2026

MIT

GUI