Geek Labs

May 9, 2026 · Fundamentals

Decode USB‑C Cable Capabilities with WhatCable: Reading E‑Marker Chips and USB‑PD

The article introduces WhatCable, an open‑source macOS menu‑bar utility that reads IOKit data to reveal a USB‑C cable’s E‑Marker specifications, supported data rates, current limits, and the negotiated USB‑PD power profile, helping users identify whether a cable can fast‑charge, transfer at high speed, or is counterfeit.