OpenNMC is an open, developer-friendly replacement for proprietary APC Network
Management Cards. It plugs directly into the standard APC SmartSlot form factor
and gives you full control over monitoring and management without vendor lock-in.

At its core, OpenNMC runs a Buildroot-based Linux system with Network UPS Tools (NUT)
handling UPS communication and a lightweight web interface for configuration,
monitoring, and control. Unlike traditional solutions, you get full system access,
allowing you to customize, extend, and integrate the device into your own infrastructure.

OpenNMC is not just a drop-in replacement. It is a platform. Whether you want a simple web
interface, deep integration into home automation, or complete control via scripts and APIs,
OpenNMC gives you the flexibility to use your UPS your way.

The Power Is Yours

If you run a homelab, server rack, or critical infrastructure, you likely rely on a UPS,
but interacting with it is often frustrating. Existing network management cards are expensive, closed, and tied to proprietary ecosystems.

OpenNMC changes that.

You can monitor your UPS through a clean web interface, integrate it into your existing systems via NUT or MQTT, or automate actions using your own scripts. For example, you might send UPS alerts into your home automation system, trigger safe shutdowns across multiple machines, or monitor power events remotely without relying on vendor services.

Because it runs a full Linux environment, OpenNMC adapts to your workflow instead of forcing you into one.

Features & Specifications

• Standard APC SmartSlot form factor
• Full Linux system based on Buildroot
• Local NUT server for UPS monitoring and control
• Web interface for configuration, monitoring, and basic control
• SSH access with full system control
• NUT proxy functionality for external systems
• MQTT client support for home automation integration
• Designed for extensibility and custom development

Hardware

• APC SmartSlot compatible interface
• NetCube Systems Nagami SoM providing an Allwinner T113-s3 with 128MiB DDR3 and 4GB eMMC
• 10/100 Mbit Ethernet
• ESP32 module for WiFi and Bluetooth connectivity
• microSD card slot for extended storage or external boot
• USB-A 2.0 host and USB-C OTG 2.0 ports for extensions such as USB HID UPS
  fallback or external network adapter for e.g. Gigabit Ethernet
• USB-C console port with integrated USB to serial interface

Software Architecture

• U-Boot Bootloader
• Buildroot-based embedded Linux (Mainline)
• NUT running internaly and proxied
• Web backend acting as NUT-proxy, MQTT-client, datalogger and UI layer
• Fully user-configurable system

Open Source

OpenNMC is designed with openness in mind. The OpenNMC carrier board is open-source hardware. It is built around a commercially available System-on-Module (SoM), which is not open hardware. This approach allows for a compact and reliable design while still keeping the majority of the system transparent and reproducible.

• Firmware and system software are open source and available now under the GPL 2.0 license, unless components specify otherwise.
• The carrier board hardware, including schematics, layout, and front panel design, will be published under a permissible license (yet to be determined).
• Users have full system access and can modify or replace any part of the software stack

Our firmware and software are available now, and hardware design files will be released during early production once our design is finalized. All of these files will be hosted in our GitLab.

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