WhatCable

Every USB-C cable looks the same. A 240W, 40Gbps Thunderbolt cable and a charge-only USB 2.0 cable from a phone box five years ago are physically identical, and there is no way to tell them apart by looking.

Most of them carry an e-marker chip that describes exactly what they support. macOS reads it. It just never shows you.

WhatCable sits in the menu bar and surfaces that data as plain English. Power delivery rating, data speed, Thunderbolt support, active or passive, vendor and product ID where the cable reports them. Plug a cable in and you get an answer in a second.

The part people find most useful is the verdict. When your Mac is charging at 60W instead of 96W, or an external drive is running at USB 2.0 speeds, the cause is the cable, the port or the device at the other end. WhatCable tells you which one, so you stop swapping cables at random.

Free to use. Pro is a one-time purchase, no subscription. No account, no telemetry, works entirely offline. Available as a direct download or via Homebrew.

Requires Apple Silicon and macOS 14 or later. Reading cable data needs IOKit access that the App Store sandbox does not allow, which is why it is distributed directly.