How does the WhatCable app work?

WhatCable reads data collected by macOS from the USB-C port controller, including e-marker details, data transfer speeds, and charging power. It uses Apple’s public APIs without requiring root access.

Can WhatCable be used on Windows or Linux?

Currently, WhatCable is only available for Apple Silicon Macs. The developer is working on a Linux port, but Windows and Android support is unlikely due to API limitations.

What data does WhatCable display?

The app shows both advertised and actual cable specs, such as data transfer speeds (e.g., USB 2.0, 10 Gbps), charging power (up to 240W), supported protocols (Thunderbolt, USB4), and real-time voltage and current metrics.

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Hardware

Free Mac App Unlocks the True Potential of USB-C Cables

July 13, 2026

Photo: The Verge

Quick answer

WhatCable is a free app for Apple Silicon Macs that analyzes real USB-C cable performance, including data transfer speeds, charging power, and supported protocols.

Developer Darryl Morley has introduced WhatCable, a free app for Apple Silicon Macs that allows users to check the real-world performance of USB-C cables and connected devices. The tool utilizes data collected by macOS via the port controller but not displayed in standard utilities. It analyzes the cable’s e-marker, actual data transfer speeds, charging power, and supported protocols like Thunderbolt or USB4.

WhatCable helps identify discrepancies between advertised and actual cable performance. For example, it can reveal if a cable marketed as supporting 100W charging and 10 Gbps speeds is actually limited to USB 2.0. This is particularly useful for users experiencing slow charging or data transfer issues. The tool also displays real-time voltage and current metrics, helping diagnose connection bottlenecks.

The app is available for free, with a paid Pro version priced at £9.99 that adds real-time power monitoring, advanced diagnostics, and a terminal view. Morley has also developed a simplified version called WhatPort, which shows current USB-C port activity. Currently, WhatCable only works on Apple Silicon Macs, but the developer plans to release a Linux port. Windows and Android support is unlikely due to API limitations.

Common questions

How does the WhatCable app work?: WhatCable reads data collected by macOS from the USB-C port controller, including e-marker details, data transfer speeds, and charging power. It uses Apple’s public APIs without requiring root access.
Can WhatCable be used on Windows or Linux?: Currently, WhatCable is only available for Apple Silicon Macs. The developer is working on a Linux port, but Windows and Android support is unlikely due to API limitations.
What data does WhatCable display?: The app shows both advertised and actual cable specs, such as data transfer speeds (e.g., USB 2.0, 10 Gbps), charging power (up to 240W), supported protocols (Thunderbolt, USB4), and real-time voltage and current metrics.

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