whatcable

# WhatCable

> **What can this USB-C cable actually do?**

**Website: [whatcable.uk](https://whatcable.uk)** (overview, screenshots, and CLI docs)

A small macOS menu bar app that tells you, in plain English, what each USB-C cable plugged into your Mac can actually do, and **why your Mac might be charging slowly**.

USB-C hides a lot under one connector. Anything from a USB 2.0 charge-only cable to a 240W / 40 Gbps Thunderbolt 4 cable, all looking identical in your drawer. macOS already exposes the relevant info via IOKit; WhatCable surfaces it as a friendly menu bar popover.

Part of a family: [**WhatBattery**](https://www.whatbattery.app) for battery health and charging, [**WhatPort**](https://www.whatport.app) for every port at once.

<a href="https://www.producthunt.com/products/whatcable?embed=true&utm_source=badge-top-post-badge&utm_medium=badge&utm_campaign=badge-whatcable" target="_blank" rel="noopener noreferrer"><img alt="WhatCable - Know what your USB-C cable can really do | Product Hunt" width="250" height="54" src="https://api.producthunt.com/widgets/embed-image/v1/top-post-badge.svg?post_id=1153432&theme=light&period=daily&t=1779720313376"></a>

[![Latest release](https://img.shields.io/github/v/release/darrylmorley/whatcable)](https://github.com/darrylmorley/whatcable/releases/latest)
[![Platform](https://img.shields.io/badge/platform-macOS%2014%2B-blue)](https://github.com/darrylmorley/whatcable)
[![License: MIT](https://img.shields.io/badge/license-MIT-green)](LICENSE)
[![WhatCable Pro](https://img.shields.io/badge/WhatCable%20Pro-%C2%A39.99-orange)](https://whatcable.uk/pro)

![WhatCable popover](docs/screenshot.webp)

## What it shows

Per port, in plain English:

- **At-a-glance headline:** Thunderbolt / USB4, USB device, Display connected, Charging only, Slow USB / charge-only cable, Nothing connected
- **Charging diagnostic:** when something's plugged in, a banner identifies the bottleneck:
  - *"Cable is limiting charging speed"* (cable rated below the charger)
  - *"Charging at 30W (charger can do up to 96W)"* (Mac is asking for less, e.g. battery near full)
  - *"Charging well at 96W"* (everything matches)
  - *"Battery full, not charging"* (plugged in, battery full, so the Mac isn't drawing power)
- **Mid-session fault warnings:** if a cable develops trouble while it's plugged in (a power overcurrent, or the connection dropping and coming back), a banner appears on the port. It reads the port's own fault counters, so it catches faults that only show up once a cable is under load.
- **Data-speed diagnostic:** a plain-English verdict on what's limiting the link, the Mac port, the cable, or the device. For example *"Cable is limiting data speed"*, *"Device runs at 10 Gbps, this is the fastest it supports, not a cable problem"*, or *"Running slower than expected"* when the link came up degraded. Shown inline, in the CLI, and in JSON.
- **Cable e-marker info:** the cable's actual speed (USB 2.0, 5 / 10 / 20 / 40 / 80 Gbps), c