Controlling Klipper-powered 3D printers from a single browser workspace, Mainsail delivers a responsive web interface for monitoring print jobs, tuning kinematics, and managing multi-printer farms in real time. Makers and print farm operators monitor extruder and heated bed temperatures, fan speeds, and toolhead coordinates live on customizable dashboard layouts. An integrated file manager and syntax-highlighted editor let you upload G-Code directly from your slicer, organize print job queues, and modify Klipper configuration files (`printer.cfg`) without opening an SSH terminal. Interactive 3D visualizations render bed mesh heightmaps for first-layer leveling diagnostics alongside a real-time 3D G-Code toolpath viewer that tracks layer progress. Multi-webcam streaming, automated timelapse recording through `moonraker-timelapse`, Spoolman filament spool tracking, and mid-print object exclusion help salvage multi-part plates when a single model detaches. You can also organize parameterized Klipper macros, switch smart relays or Tasmota power plugs, and audit historical job success rates and filament consumption. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-3.0 licensed.