This free Mac app reveals the truth about your mystery USB-C cables

Key Points:

• WhatCable is a free USB-C cable tester app for Apple Silicon Macs that reads detailed data about connected cables and devices by accessing information already collected by macOS but not normally shown to users.
• The app uses Apple’s public APIs to read e-marker data, negotiated connection speeds, power delivery, and device info without requiring root access, providing real-time insight into cable performance and bottlenecks.
• Testing with WhatCable revealed accurate reporting of charging wattage and connection speeds, helped identify worn-out cables, and exposed some cables falsely advertising higher data speeds than they actually support.
• WhatCable’s creator, Darryl Morley, plans to keep the core app free, offers a paid Pro version with extra features, and is developing a simpler WhatPort app; a Linux port is in progress, but Windows, Android, and iOS versions are unlikely due to hardware and API limitations.
• The app offers a more detailed and user-friendly alternative to inexpensive hardware testers, making it a valuable tool for Mac users wanting to verify USB-C cable and device capabilities.