WhatCable

WhatCable is a free, open-source macOS menu bar app for Apple Silicon Macs (macOS 14+) that reads USB-C and USB Power Delivery data from IOKit and presents it in plain English. It identifies cable speed (USB 2.0, USB 3.2, USB4, Thunderbolt), charging power limits, e-marker chip details (vendor, current rating, capabilities), and connected devices. Key features include charging bottleneck detection, data-speed bottleneck analysis, cable trust signals (flags suspicious e-marker values), a bundled CLI tool for terminal use and scripting, and a public cable database. The free version covers cable identity, charging info, device detection, and bottleneck verdicts. WhatCable Pro (£4.99 one-time) adds live power metering, port health counters, PD contract inspection, DP Alt Mode details, and raw VDO fingerprints. No telemetry, no network requests, fully open source under MIT license.