How many USB-C cables have you accumulated over the years? Chargers for smartphones, hubs for monitors, peripherals. They often look identical, but hide enormous differences in performance. Some support fast charging at 100 watts, others stop at 15. Some transfer data at 40 Gbps, others at 480 Mbps. Until now, the only way to discover their true capabilities was to buy an expensive hardware tester or rely on trial and error. But now there is a free and intelligent solution for Mac users with Apple Silicon chips: it's called WhatCable.
A free app that analyzes USB-C cables in seconds
WhatCable is a native macOS application that leverages the hardware features of M1, M2, and later chips to read the cable's identification information. When you plug a USB-C cable into your Mac, the app displays in real time the supported data transfer speed, maximum power delivery, and compliance with USB standards. There is no need to disassemble anything or interpret mysterious codes: the interface is clear and immediate.
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Many users are unaware that every USB-C cable contains an identification chip called an e-marker. This chip communicates the cable's specifications to the device. However, the operating system often does not show this information. WhatCable makes it accessible with a single click. Simply launch the app and connect the cable: within seconds, a summary card indicates whether the cable is suitable for fast charging, 4K video, or large file transfers.
A problem Google solved years ago, but Apple hasn't
Google implemented a similar feature in Chrome OS several years ago, allowing users to see cable capabilities directly in the system. Many experts have suggested that Apple adopt the same solution in macOS, but it hasn't happened yet. The lack of a built-in tool has prompted independent developers to create alternatives like WhatCable. The app is available for free on the Mac App Store and requires no special permissions.
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The USB-C cable problem is well known: all connectors look the same, but specifications can vary enormously. A cheap cable may not support Power Delivery, or may be limited to USB 2.0 standards. With the rise of devices requiring high power, such as 140-watt MacBook Pros, knowing which cables are suitable is essential to avoid slow charging or damage.
How to use WhatCable and what to look for
Downloading WhatCable is simple: visit the App Store and install it. Once launched, the app shows a list of detected cables. For each, it displays the maximum voltage and current, transfer speed, and USB standard (e.g., USB 3.2 Gen 2 or Thunderbolt 4). You can also test actual charging by connecting a device and monitoring power in real time.
If you discover a cable is slower than expected, don't throw it away: it may still be useful for low-power devices. But for critical applications, such as powering a laptop during work, it's better to use certified cables. WhatCable helps you distinguish quality cables from poor ones without spending a cent. For more on Apple's ecosystem, check out our article on the AirPods Pro 3 at a discounted price.
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An alternative to now-hard-to-find hardware testers
A few years ago, there was an inexpensive USB-C tester, sold for about $8, that let you evaluate cable capabilities with a simple LED indicator. Unfortunately, that product was discontinued and never replaced by anything as intuitive and cheap. WhatCable fills this gap by offering a software solution that is just as effective, but free. The only requirement is a Mac with Apple Silicon, but given the prevalence of these chips, most users can benefit.
To better understand the differences between USB standards, check the Wikipedia page on USB-C. Also, if you're interested in iOS 27 news, read our article about the public beta arriving soon.
Source: https://www.theverge.com/gadgets/963759/whatcable-usb-c-cable-tester-app-mac
