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

A Bitmoor product macOS menu bar diagnostics for USB-C Plug in a cable. WhatCable shows its speed, power capability, display path, and the weak link in your connection, using what macOS reports, not what the packaging promises. Need deeper diagnostics? Explore WhatCable Pro Open source, Pro optional Apple Silicon, macOS 14+ Signed and notarised Available in 19 languages Answers, not raw dataSee what is happening across the whole connection. A cable never works alone. WhatCable reads the port, cable, charger, adapter and connected device together, then explains the result in plain English. ChargingWhy is this Mac charging slowly? 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. Charger and cable are fine. The Mac will draw up to 94W when it needs to. Cable identityWhat kind of cable is this? Read the cable's e-marker identity, advertised speed, power rating and active transports. Turn on technical details when you need the underlying values from macOS. USB4 Gen 4 at 80 Gbps. Rated for up to 240W. How WhatCable knowsClaims are useful. Observed behaviour is better. 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. 125 cable observations in the public databaseReported through WhatCable Searchable by vendor, speed and identity Nothing is uploaded without your action Cables seen by WhatCable users. Search reported cables by vendor, speed and identity, or see whether yours has appeared before. Browse all cables USB4 80 GbpsCalDigit TB5 cable240W, passive USB 2.0Anker 333 nylon100W, passive USB 3.2 Gen 2Monoprice Essentials100W, passive FeaturesPlain 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 bottlenecksSee whether the cable, charger, or Mac is limiting the current charge rate, with the negotiated power profile highlighted. Mid-session fault warningsIf 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. Data-speed bottlenecksA 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 bottlenecksWhen 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 dataDecode 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. Active transportsIdentify USB 2, USB 3, USB4, Thunderbolt, and DisplayPort paths under the physical port where they are connected. Engineer modeOption-click or enable raw details to reveal the underlying IOKit properties when you need the registry-level facts. Connected devicesEvery 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. Built for macOSA focused menu bar app on Apple Silicon Macs. No helper daemon, no private API, no background uploads. CLIThe 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. Full-screen live dashboard of ports, power, and Thunderbolt with --dashboard (Pro).

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. 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 SettingsMake 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. NotificationsGet alerts when cables connect or disconnect. Dock modeRun as a regular window instead of a menu bar icon. Launch at loginStart automatically so it is ready when you plug in. Hide empty portsOnly show ports with something plugged in. ProNeed more? Pro goes deeper. The free app answers the everyday questions. Pro adds history, live measurements, and the deeper evidence needed for difficult faults and repeat testing. £9.99 one-time. Works on up to 2 Macs. See all 16 Pro features Cable historyAdd a cable, give it a name, and WhatCable records how it performs over time, with a verdict per cable. Negotiation DiagnosticsMac port, cable, and device support side by side, with the weak link highlighted. Live power meteringWatts, amps, and voltage per port, updating every 2 seconds. FAQCommon questions. Does it work on Intel Macs?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.