PowerScope — oxblog

ChargerLAB only provides a Windows app for the Power-Z KM003C. I wasn’t going<br>to install a whole separate operating system just to use one USB power meter,<br>so I built PowerScope. It graphs live voltage, signed current, power,<br>temperature and USB rails at up to 100 samples per second; records sessions;<br>exports CSV and JSON; and captures and decodes USB Power Delivery traffic and<br>cable E-Markers.

PowerScope reading a KM003C directly from the browser — it’s my iPhone charging

Everything runs locally in the browser. WebUSB talks to the meter, Web Serial<br>provides its separate control channel, Go/Wasm parses measurements and USB-PD<br>traffic, and IndexedDB stores recordings. The site serves static assets;<br>device data stays in the browser.

Try the web app in Chrome or Chromium.