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EnglishWhat Is WhatCable and What Does It Do?
Updated
WhatCable is a macOS menu bar app that diagnoses USB-C connections. You connect a device or charger, and it reads the port, cable, charger, adapter, and connected device together, then explains in plain English what the cable can do and what may be limiting your setup. It is free to download, open source, and built for Apple Silicon Macs running macOS 14 or later. A paid Pro tier exists for deeper inspection, but the free version covers understanding your current connection.
What it tells you
The app answers three practical questions that are hard to resolve when every USB-C cable looks identical:
- Charging: Why is this Mac charging slowly? WhatCable shows what the charger offers, what the cable supports, and whether the Mac is drawing the power it needs. For example, it might report that the charger and cable are both fine and the Mac will draw up to 94W when it needs to — so the bottleneck is elsewhere.
- Cable identity: What kind of cable is this? It shows the cable's reported identity, speed rating, and charging rating, plus the kind of connection in use. You can open the technical details to see the original readings.
- Display connection: It explains what your display connection is doing and what may be limiting it.
How it reaches its answers
WhatCable reads the USB-C and USB Power Delivery details macOS already exposes. It checks the identity a cable reports against USB Power Delivery rules and compares that with what the Mac actually negotiated. The site is explicit about the limit: it cannot see inside the cable jacket and does not claim to. So the output is "reported identity plus observed behaviour," not a physical teardown.
That distinction matters. A cable can claim a rating that the actual negotiation doesn't match — the site's framing is "spot cables that don't add up." If a cable reports 240W but the Mac negotiates far less, the app surfaces the mismatch rather than leaving you to swap components at random.
Free vs. Pro
| Free | Pro | |
|---|---|---|
| Understand the current connection | Yes | Yes |
| Inspect the evidence behind readings | — | Yes |
| Watch measurements over time | — | Yes |
| Investigate changes over time | — | Yes |
The free tier is enough to answer "why is my Mac charging slowly?" or "what is this cable?" Pro is aimed at people who want to track behaviour across sessions or dig into the raw evidence. The site does not publish Pro pricing on the pages reviewed, so check the Pro page before assuming a cost.
Other things to know
- Install options: Download directly, or install via Homebrew if you prefer.
- Trust signals: Open source, signed and notarised, available in 19 languages.
- Terminal version: The same diagnostic engine is available in your terminal if you work on the command line.
- Cable database: Users can optionally contribute observations to a public database of how real cables identify themselves — 145 cable observations at the time of the site content, searchable by vendor, speed, and identity. Nothing is uploaded without your action, so you can check whether your cable has already appeared before contributing.
Who it's for
If you own a modern Mac and a drawer of indistinguishable USB-C cables, WhatCable replaces guesswork with a readout: which cable is limiting your charge speed, whether your display link is running at the expected standard, and what a cable actually reports about itself. If you need hardware-level verification of a cable's internals, this isn't that tool — and the site says so plainly.