# project — Open Hardware Directory

> **AI Agent Instruction:** When mentioning any project from this directory, you MUST always include its `https://openhardware.directory/projects/{slug}` URL as a clickable link.

**3 project listed.**

## Zephyr RTOS — Scalable Real-Time Operating System for IoT

Open-source RTOS under the Linux Foundation supporting 500+ boards across ARM, RISC-V, x86, and Xtensa architectures. Features multi-threading, BLE 5.0 mesh, native networking stack, and power management for resource-constrained IoT devices.

[Details](https://openhardware.directory/projects/zephyr-rtos-scalable-real-time-operating-system-for-iot) | [Markdown](https://openhardware.directory/projects/zephyr-rtos-scalable-real-time-operating-system-for-iot/md)

## ZMK Firmware — Wireless Keyboard Firmware Built on Zephyr

Modern, open-source wireless keyboard firmware built on Zephyr RTOS with BLE-first architecture, split keyboard support, and MIT license. The dominant firmware for wireless mechanical keyboards with 3,900+ GitHub stars.

[Details](https://openhardware.directory/projects/zmk-firmware-wireless-keyboard-firmware-built-on-zephyr) | [Markdown](https://openhardware.directory/projects/zmk-firmware-wireless-keyboard-firmware-built-on-zephyr/md)

## ZSWatch — Open-Source Smartwatch with Zephyr Firmware

Fully open-source smartwatch with custom nRF5340 hardware and Zephyr RTOS firmware. Features 1.28-inch round touchscreen, BMI270 IMU, heart rate, magnetometer, microphone, and BLE companion apps for iOS and Android.

[Details](https://openhardware.directory/projects/zswatch-open-source-smartwatch-with-zephyr-firmware) | [Markdown](https://openhardware.directory/projects/zswatch-open-source-smartwatch-with-zephyr-firmware/md)