This project is an Arduino communication library that enables ESP8266, ESP32, and Arduino boards to monitor and control Klipper 3D printers through the Moonraker API.
The example code includes fully working firmware that periodically connects to Moonraker using an ESP32, ESP8266, or an Arduino paired with a W5100/W5500 Ethernet Shield. It demonstrates:
Retrieving server information
Querying printer status and statistics
Reading current position, temperature, power output, and active print job details
Executing emergency stop and temperature safety checks
All of these features are implemented and functional in the included examples.
๐Features
Core Functionality
Real-time printer status monitoring (status, position, temperature, etc.)
Also available for manual installation via GitHub Releases or source download
๐System Architecture
Core Components
MCU
ESP8266 (Wi-Fi)
ESP32 (Wi-Fi)
Arduino + W5100/W5500 Ethernet Shield
Server
3D printer running Klipper firmware
Moonraker API server
Network
Wi-Fi (built into ESP8266/ESP32)
Ethernet (via W5100/W5500 shield)
HTTP/JSON-based REST API calls to Moonraker
Data Flow
The MCU connects to the LAN via Wi-Fi or Ethernet.
The KlipperApi object sends requests to multiple Moonraker server endpoints.
The MCU receives the JSON response into an internal buffer (default 2048 bytes) and parses it into optimized structures.
User code can then utilize these structures to perform:
Status display (Serial / Web / LCD)
Temperature safety checks
Print control
And other application logic
๐Role and Application of the W5500
In the KlipperAPI project, the W5500 is used as the key network module that enables wired Ethernet communication between the Arduino board and the Klipper/Moonraker server. In environments where Wi-Fi is unstable or where 3D printer control requires consistent latency and reliable response times, the W5500 provides the most dependable connection method.
Main Roles of the W5500
Wired Moonraker Connectivity
Even low-spec MCUs such as Arduino Uno/Mega/Leonardo can communicate directly with the Klipper/Moonraker server through the W5500.
Ideal for 3D printer control scenarios that require high speed and stable connectivity.
Printer Status Queries and Data Reception
Core KlipperAPI functionsโsuch as getServerInfo(), getPrinterInfo(), and getPrinterStatistics()โsend requests to Moonraker over the W5500 network path.
Temperature, position, progress, and other data are received reliably thanks to hardware-based packet handling.
Sending Control Commands
Sends G-code (sendGcode()), print start/pause/cancel operations, temperature settings, axis movement commands, and more through the W5500.
Provides more stable, lower-latency control than Wi-Fi, with reduced risk of communication errors.
Ensuring Network Stability
Example code includes Ethernet state checks, link detection, and retry logic for improved robustness.
Supports both DHCP and static IP configurations, with KlipperAPI running reliably on top of the EthernetClient.
๐Market & Application Value
Application Areas
External control panels and remote control terminals for Klipper 3D printers
Standalone status displays (small LCD/OLED) and notification devices (buzzer, LED)
Integration with Klipper for controlling peripheral equipment such as lighting, fans, and environmental sensors
Advantages Over Existing Approaches
Traditionally, control was mainly done through web UIs (Fluidd/Mainsail) or applications running on a Raspberry Pi; this library enables direct control from low-cost MCU boards
With only a network connection, a single board can monitor multiple printers or serve as a dedicated HMI
Expansion Potential
Can be used as a management node in IoT devices or smart factoryโstyle 3D printer farms
Well-suited as a bridge connecting industrial Ethernet, sensors, and printers
๐External Indicators
Currently, the number of stars and forks on GitHub is low, and the library has a strong personal-project nature.
However, resources such as FEATURES.md, the example code folder, and the detailed API documentation in the README are well organized, making it valuable for technical experimentation and reference purposes.
๐WIZnet Strategic Value
Representative Use Case for Ethernet + Klipper Integration
By applying a KlipperAPI-style library to boards using WIZnet chips, it becomes possible to create a wired, low-latency 3D printer controller reference design.
Entry Point Into the 3D Printer Market
The number of 3D printer users adopting Klipper is growing rapidly, and there is strong demand in printer farms, shared workspaces, and FabLabs for printer status monitoring and centralized management.
WIZnet can enter the 3D-printer networking module market by offering a bundled solution in the form of โEthernet + Klipper-compatible board/module + library package.โ
Piggybacking on the ESP Ecosystem
Since KlipperAPI supports ESP8266 and ESP32, combining ESP with a WIZnet Ethernet module enables a dual Wi-Fi + Ethernet environment.
Creating a โKlipper-dedicated network expansion moduleโ as a WIZnet UCC reference project would naturally expose WIZnet chips to the ESP maker community.
In the Klipper user community, there have been active discussions about implementing Ethernet connectivity by pairing an MCU with an SPI-to-Ethernet chip such as the WIZnet W5500, ENC28J60, or LAN8720. Overall forum feedback has been positive, with virtually no objections to combinations like โSTM32 + W5500 (or ENC28J60/LAN8720)โ.
๐Summary
KlipperAPI is a meaningful library that clearly showcases the concept of directly controlling Klipper using an MCU with Ethernet or Wi-Fi. It has the potential to serve as a bridge project that connects both the ESP ecosystem and the Klipper community.
In the Klipper user community, there have been active discussions about implementing Ethernet connectivity by pairing an MCU with an SPI-to-Ethernet chip such as the WIZnet W5500, ENC28J60, or LAN8720. Overall forum feedback has been positive, with virtually no objections to combinations like โSTM32 + W5500 (or ENC28J60/LAN8720)โ.
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