When the power blinks at 3 a.m., NUT WebGUI is the page that tells you whether the UPS in the closet is coasting or dying, without a serial cable in sight. Point it at one or several Network UPS Tools servers and it polls charge, load, input voltage, and estimated runtime, refreshing critical status every couple of seconds while background variables update on a calmer thirty-second cadence. The dashboard renders device cards, gauges, sparklines, and a topology view of how units chain together, and it stays readable on a phone when you are standing in front of a humming rack. Authorized users can issue instant commands, set variables, or trigger a forced shutdown from the browser, while everyone else gets a strictly read-only view. A JSON API under /api serves device lists, variables, and instant commands to your own scripts, health and readiness probes fit container orchestrators, and OpenMetrics output feeds Prometheus without extra exporters. The whole thing is a single small binary that runs happily on a Raspberry Pi, an old ARM board, or a RISC-V box, reads one TOML file, and supports multi-user sign-in with scoped API keys when you share it with a team. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.