Connect a device or charger. See your cable’s reported speed and charging capability, understand your display connection, and find what may be limiting the setup.
Free: understand the current connection.
Pro: inspect the evidence, watch measurements and investigate changes over time. Explore WhatCable Pro
As featured in
“Finally tells you what your USB-C cables can actually do.”
A cable never works alone. WhatCable reads the port, cable, charger, adapter and connected device together, then explains the result in plain English.
See what the charger offers, what the cable supports, and whether the Mac is drawing all the power it needs. WhatCable explains the result instead of leaving you to swap components at random.
See the cable’s reported identity, speed and charging rating, plus the kind of connection it is using. Open the technical details when you want to see the original readings.
See what the wires and identity chip do in our interactive cable diagram →
WhatCable reads the identity a cable reports, checks it against USB Power Delivery rules, and compares it with what the Mac actually negotiated. It cannot see inside the cable jacket and never pretends it can.
Contributed observations build a public record of how real cables identify themselves across real hardware.
Search reported cables by vendor, speed and identity, or see whether yours has appeared before.
WhatCable reads the USB-C and USB Power Delivery details macOS already exposes, then turns them into useful labels, charging diagnostics, and port-by-port device context.
See whether the cable, charger, or Mac is limiting the current charge rate, with the negotiated power profile highlighted.
If a cable develops trouble while it is plugged in (an overcurrent or the connection dropping and reconnecting), a banner appears on the port. Catches faults that only show up under load.
A plain-English verdict on what is limiting the link: the Mac port, the cable, or the device, so you know whether a faster cable would actually help.
When a monitor is connected, see whether the link is carrying its full resolution and refresh, or falling short, and whether an adapter, the cable, or the selected mode is the limit.
Decode cable speed, current rating, vendor identity, and USB PD capability flags from marked USB-C cables, including USB-IF certification read straight off the cable.
Identify USB 2, USB 3, USB4, Thunderbolt, and DisplayPort paths under the physical port where they are connected.
Option-click or enable technical details to see the original information macOS reports about the connection.
Every device sits inside the thing it is actually plugged into, not a flat pile. Hubs are hidden by default, and each device says how many it is sitting behind.
A focused menu bar app on Apple Silicon Macs. No helper daemon, no private API, no background uploads.
The bundled CLI gives you quick snapshots, structured JSON for scripts, and watch mode when you are swapping cables during testing.
jq for repeatable diagnostics.--watch.--dashboard (Pro).$ whatcable USB-C Port 1 ✓ Charging well at 96W Cable: 5A, 100W, USB4 40 Gbps Charger: 5V / 9V / 15V / 20V PDOs USB-C Port 2 ! Cable is limiting charging speed Cable: 3A, 60W, USB 2.0 Device: External SSD, USB 10 Gbps
WhatCable checks the e-marker data against the USB Power Delivery spec. When something looks unusual, an orange card appears with the details. It is not a guarantee the cable is fake, but it tells you where to look.
WhatCable stays out of the way until you need it. A few settings let you control how it runs and what it shows.
Get alerts when cables connect or disconnect.
Run as a regular window instead of a menu bar icon.
Start automatically so it is ready when you plug in.
Only show ports with something plugged in.
Same plug, different insides: explore our 3D cable diagram to compare basic USB-C, Thunderbolt 4 and Thunderbolt 5.
No. WhatCable needs Apple Silicon (M1 or later). This is measured, not assumed: every Intel Mac in our community diagnostic data reports its USB-C port controllers as empty, so the USB-PD state and cable e-marker data WhatCable is built on never appear on those machines at all. Thunderbolt link data is still there on Intel, but the port-controller layer WhatCable reads is not.
Yes. The WhatCable app is free and open source under the MIT licence. No ads, no tracking. WhatCable Pro (£9.99, optional) adds advanced diagnostics for power users. See what's included.
Pro helps you investigate further: keep a cable history, watch power readings, understand a slow connection and check why a screen is not performing as expected. It is a one-time £9.99 purchase for up to two Macs, with no subscription. See the features and comparison.
Technical detail: The tools include Negotiation and Display Diagnostics, port health counters, the USB Power Delivery contract inspector and raw cable identity fields. Each gives more context behind the main explanation.
No analytics, no telemetry, and nothing about you or your cables ever leaves your Mac. In the free app the one routine network call is a version check against the public GitHub Releases API, roughly every 6 hours. WhatCable Pro adds one more: a licence check when you activate your key, then once each time the app launches. That call sends only the key and your Mac's hardware UUID, which is how the two-Mac limit is enforced. Diagnostic data only goes anywhere if you explicitly choose to contribute it. Check the source on GitHub if you want to verify.
No. The e-marker is the cable’s digital label, but WhatCable also uses the connection information your Mac provides. It compares the port, cable and connected device, and checks display links too. This helps explain why the connection is working at a particular speed or charging rate.
Technical detail: On Thunderbolt and USB4 connections, controller reports can show the negotiated link speed. That confirms the speed reached in that connection, not the cable’s absolute maximum. A compatible passive cable with an older 40 Gbps identity may legitimately carry newer 80 Gbps signalling. Missing faster-link evidence does not prove a lower physical limit.
The cable may have no identity chip, or your Mac may not have read it yet. Try connecting a charger, dock or device at the far end, then check again. Missing information alone does not mean the cable is broken.
Technical detail: Some basic USB 2.0 cables do not require an e-marker. Full-featured cables and cables carrying more than 3 A do. Whether macOS exposes the identity also depends on the port and connected equipment; connecting another device can help trigger a read but does not guarantee one.
Not definitively. WhatCable helps you investigate inconsistent reports and connection problems. A missing manufacturer or certificate alone does not prove a cable is counterfeit.
Technical detail: The trust checks examine identity and capability fields against USB Power Delivery rules. Malformed or contradictory fields are different from missing information. The app cannot inspect the physical wiring or authenticate every product label.
19, and the diagnostic verdicts are translated too, not just the menus: Armenian, Brazilian Portuguese, Dutch, English, French, German, Hindi, Italian, Japanese, Korean, Latvian, Norwegian, Polish, Russian, Simplified Chinese, Spanish, Traditional Chinese, Turkish, and Ukrainian. WhatCable follows your Mac's language by default, or you can pick one in Settings. Translations are community-refinable, so if something reads oddly in your language, open an issue and we'll fix it.
Menu bar app, command-line tool, or both. Signed, notarised, and universal. Requires macOS 14 or later on Apple Silicon.
Menu bar app plus the whatcable CLI on your PATH.
brew install --cask darrylmorley/whatcable/whatcable
Just the whatcable command, no menu bar app. Same signed binary, useful for terminal-only setups and scripts.
brew install darrylmorley/whatcable/whatcable-cli
Grab the latest .zip from GitHub Releases. The release page also has a CLI-only zip. Drag WhatCable.app into Applications.
WhatCable explains the connected setup. These companion apps add a closer look at battery health and a dedicated overview of your Mac’s ports.
Take a closer look at the battery itself: Unrounded health, live charge and discharge in watts, per-cell readings from the pack, and where the charge went overnight.
Visit whatbattery.app →
A dedicated overview of your Mac’s ports: connection types, speeds, signal paths and available live power readings in one place.
Visit whatport.app →