Free macOS App Reveals the Real Speed and Charging Power of Your USB-C Cables
USB-C was meant to simplify everything. One small reversible connector for charging, data transfer, displays, docks, and accessories sounds ideal. In reality, many USB-C cables look almost identical while offering very different performance.
Some cables only support slow USB 2.0 data transfer at 480 Mbit/s. Others can handle extremely fast speeds of up to 120 Gbit/s. Charging support can also vary widely, from basic 5-watt output to powerful 240-watt USB-C Power Delivery. The problem is that most cables are not clearly labeled, leaving users guessing which cable is best for charging a MacBook, connecting a monitor, or transferring large files.
A free macOS app called WhatCable aims to make that confusion much easier to manage.
WhatCable is designed for Mac users who want to identify the capabilities of their USB-C and MagSafe cables. After launching the app, it adds an icon to the macOS menu bar. From there, users can view information about the USB-C ports on their Mac, including the maximum supported data rate and the available USB-C Power Delivery profiles.
This can be especially useful if you own a MacBook Air, MacBook Pro, Mac mini, or iMac and regularly switch between multiple chargers, hubs, docks, external drives, and monitors. Instead of testing cables through trial and error, the app helps reveal whether a cable is suitable for fast charging, high-speed data transfer, or running external displays through a dock.
For example, if your laptop charges slowly or continues losing battery while plugged in, the cable may not support enough wattage. If file transfers feel unusually slow, the cable may be limited to USB 2.0 speeds. If an external monitor connected through a dock is not running at its full resolution or refresh rate, the cable or connection bandwidth may be the bottleneck.
WhatCable can also provide details about connected devices, making it useful for diagnosing setups involving USB-C hubs, docking stations, monitors, storage devices, and chargers. For users with a drawer full of nearly identical cables, this kind of information can save time and frustration.
However, the app is not perfect. Some low-cost USB-C cables do not include an E-Marker chip, which means they may not provide full information about their capabilities. In those cases, WhatCable may be able to show charging power details but not the cable’s data transfer speed.
There can also be occasional detection issues. For instance, a Thunderbolt 3 cable connected to a regular USB device may be identified based on the active USB connection rather than the cable’s full Thunderbolt capability. This can make the cable appear slower than it really is in certain situations.
Even with those limitations, WhatCable can still be a helpful tool for many Mac users. It gives quick insight into cable performance and helps explain why some USB-C cables work better than others for charging, data transfer, or display output.
The standard version of WhatCable is free to use. A paid WhatCable Pro version is also available as a one-time purchase, offering additional details for users who want deeper technical information about their USB-C and MagSafe connections.
For anyone who regularly uses USB-C accessories with a Mac, this app offers a simple way to bring order to cable chaos. Instead of guessing which cable supports fast charging or high-speed transfers, Mac users can finally get a clearer look at what their USB-C cables are actually capable of.
