USB-C has long promised to simplify things with a universal connector, but many users have found the opposite to be true, particularly in regard to USB-C cable speed. Two wires can seem the same but produce wildly different performance. You can move files around at 40 Gbps and run a bunch of monitors, but there’s another one that’s stuck at modest USB 2.0 rates and very rudimentary charging.
A new free macOS app wants to remove that guesswork, presenting you exactly what each cable is capable of.
Developed by Darryl Morley, WhatCable is a free, open-source application designed for Apple Silicon Macs that provides real-time insights into connected USB-C cables. Rather than conducting tests, it retrieves data directly from the Mac’s hardware through macOS APIs, making it a preferred choice for 9to5Mac readers.
The app reveals key details such as the following:
- Supported USB-C cable speed
- Maximum charging power
- USB and Thunderbolt compatibility
- Display capabilities
- Presence of an e-marker chip
- Connected device information
WhatCable accesses data from the USB power delivery controllers integrated into Apple Silicon Macs. Many modern cables have e-marker chips that report their capabilities (including USB-C cable speed), and the app just displays that info in an easy-to-read format.
The app requires macOS 14 Sonoma and does not support Intel Macs, as they lack access to the same hardware data needed to analyze USB-C cable speed. Windows and iPhone versions are not available yet, though Linux support is in development.
The base version is free and includes essential cable diagnostics. A paid WhatCable Pro upgrade adds advanced features like power monitoring, cable history, and deeper troubleshooting tools.
As USB-C becomes the standard across devices, understanding USB-C cable speed is increasingly important. Tools like WhatCable help users quickly identify performance limitations and avoid guesswork.
