WhatCable: Know what your USB-C cable can really do

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The problem<br>Every USB-C cable looks the same. They are not.

Your drawer is full of identical-looking cables. Some charge at full speed, some crawl. Some carry video, some can barely handle a mouse. The connector tells you nothing.

USB 2.0480 Mbps, 60W<br>Charges slowly, no video output. Fine for a keyboard, terrible for an external display or fast storage.

USB440 Gbps, 100W<br>Fast data, good charging. Handles most displays and external SSDs without issues.

Thunderbolt 440 Gbps, 240W<br>Full speed data, maximum charging, dual 4K displays. The cable your dock needs but you cannot tell by looking.

Features<br>Plain answers for cables that all look the same.

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.

Charging bottlenecks<br>See whether the cable, charger, or Mac is limiting the current charge rate, with the negotiated power profile highlighted.

Data-speed bottlenecks<br>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.

Display bottlenecks<br>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.

Cable e-marker data<br>Decode cable speed, current rating, vendor identity, and USB PD capability flags from marked USB-C cables.

Active transports<br>Identify USB 2, USB 3, USB4, Thunderbolt, and DisplayPort paths under the physical port where they are connected.

Engineer mode<br>Option-click or enable raw details to reveal the underlying IOKit properties when you need the registry-level facts.

Device identity<br>Match storage, hubs, docks, and peripherals back to the port they are using, including the negotiated USB speed.

Built for macOS<br>A focused menu bar app on Apple Silicon Macs. No helper daemon, no private API, no background uploads.

Speaks your language<br>Fully translated into 19 languages, the diagnostic verdicts included, so you read what your cable is doing in your own language. Follows your Mac, or pick one in Settings.

Free, with optional Pro<br>See what your cables are doing right now.

The free app tells you what your cable can do and, in plain English, where the bottleneck is. Pro shows you the full picture: live power flowing through each port, real-time PD contracts, the full negotiation breakdown of every connection, port health over time, and the raw VDO fingerprints behind every cable.

14 advanced features, £9.99 one-time, works on up to 2 Macs.

Unlock Pro

CLI<br>The same diagnostic engine in your terminal.

The bundled CLI gives you quick snapshots, structured JSON for scripts, and watch mode when you are swapping cables during testing.

Readable summaries for quick cable checks.

Pipe JSON into jq for repeatable diagnostics.

Live updates as ports connect and disconnect with --watch.

~ whatcable

$ whatcable

USB-C Port 1<br>✓ Charging well at 96W<br>Cable: 5A, 100W, USB4 40 Gbps<br>Charger: 5V / 9V / 15V / 20V PDOs

USB-C Port 2<br>! Cable is limiting charging speed<br>Cable: 3A, 60W, USB 2.0<br>Device: External SSD, USB 10 Gbps

Cable trust signals<br>Spot cables that don't add up.

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.

Vendor ID checked against the USB-IF published list.

Speed and current fields validated against PD spec ranges.

Reserved bit patterns and zero-value metadata flagged.

Cable trust flags

Vendor ID is 0x0000 (not registered with USB-IF)

Cable latency field uses a reserved value

Claims 5A current but reports USB 2.0 speed

Cable database<br>Cables seen by WhatCable users.

Every cable reported through the app gets added to a public, searchable database. Check if your cable has been seen before, or browse what others are using.

USB4 80 GbpsCalDigit TB5 cable 240W, passive

USB4 40 GbpsUGREEN Revodok Max 213 100W, passive

USB 2.0Anker 333 nylon 100W, passive

USB 3.2 Gen 2Monoprice Essentials 100W, passive

USB4 40 GbpsCalDigit TS4 bundled 100W, passive

Browse all cables

Settings<br>Make it yours.

WhatCable stays out of the way until you need it. A few settings let you control how it runs and what it shows.

Notifications<br>Get alerts when cables connect or disconnect.

Dock mode<br>Run as a regular window instead of a menu bar icon.

Launch at login<br>Start automatically so it is ready when you plug in.

Hide empty ports<br>Only show ports with something plugged in.

Pro<br>Need more? Pro goes deeper.

The free app covers cable identity, charging info, device detection, and a plain-English verdict on what is limiting each link. Pro shows the full breakdown: Negotiation Diagnostics with Mac port, cable, and device side by side and the...