Running out of filament mid-print ruins multi-hour 3D printing jobs, and Spoolman solves this by tracking every gram of plastic across your entire workshop in a centralized, self-hosted inventory database. Connected directly to Klipper, Moonraker, Mainsail, Fluidd, OctoPrint, and OctoEverywhere, the service deducts filament weight automatically over live WebSockets as your extruders run. You can import manufacturer specifications from the community SpoolmanDB catalog, filter your library by color similarity or material type, and organize spools on a drag-and-drop board grouped by storage location or custom fields. A built-in label designer generates printable QR code sheets containing spool metadata, while NFC and RFID tag scanning lets you tap a physical roll against an ESPHome reader or Android phone to pull up its record immediately. Multi-printer workshops can monitor concurrent consumption from several machines simultaneously, expose inventory metrics to Prometheus and Home Assistant, and query stock levels through a Model Context Protocol (MCP) server. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.