Marlinraker is a tool that connects an external device to your Marlin 3D Printer via serial and emulates Moonraker API endpoints. This enables you to use your favorite Klipper interfaces like Mainsail and Fluidd with Marlin machines. The Node.js runtime makes it performant enough to easily run on low-power SBCs like the Raspberry Pi Zero W and even on Windows machines.
For more information, check out the official documentation.