Cable Detective icon

What's actually plugged into each port.

Cable Detective reads the macOS I/O Kit registry and tells you exactly what your USB-C, Thunderbolt, and MagSafe ports are doing right now. On your Mac. Nothing leaves the device.

One-time €9.99. No subscription. No account. No cloud.
Cable Detective showing a MagSafe 3 port charging at 86 W, with cable e-marker, power, speed, and protocol details.

Plug it in. See what it really is.

USB-C ports look identical. They behave wildly differently. Cable Detective shows the truth for each one.

Every port. Every detail.

A live walkthrough of one MacBook Air. Four physically identical USB-C ports doing four very different jobs - and the Local AI panel that explains each one in plain English, on-device.

Cable Detective showing MagSafe 3 #1 charging at 65 W. The hero card decodes the cable as a genuine Apple MagSafe 3 charging cable paired with a 65 W charger.

MagSafe 3 - Power-only cable, 65 W of 65 W negotiated, USB Power Delivery contract decoded, no overcurrent events.

Cable Detective showing USB-C #2 with an Anker hub carrying USB data plus DisplayPort video at HBR2.

USB-C with hub + video - Anker hub, six USB devices behind it, DisplayPort 5.4 Gbps (HBR2) on 2 lanes, USB 2.0 lanes carrying the data.

Cable Detective showing USB-C #1 with a USB 2.0 link to an Apple MagSafe Charger - the cable is wired for SuperSpeed but the link runs USB 2.

USB-C 2 link - The cable is wired for USB 3.x SuperSpeed but negotiated down to USB 2 only. The Mac is powering the device at 15 W. The detail page tells you which side gave up.

Cable Detective showing USB-C #4 with a cable seated but nothing connected - waiting state, no power flowing, configuration channel only.

Cable seated, nothing talking - The Mac sees the plug but no device is negotiating. Likely the other end is unplugged, the device is off, or it's a charge-only cable with no charger attached.

Cable Detective Settings - Local AI tab. The Apple Intelligence section has buttons that deep-link directly to the macOS Apple Intelligence settings pane and to Apple's official 'Turn on Apple Intelligence' guide.

Local AI - Apple Foundation Models, on-device only. Buttons deep-link straight to the macOS Apple Intelligence pane and the official Apple activation guide. Nothing leaves your Mac.

Cable Detective Settings - General tab. Live cable monitoring section explains that verdicts refresh automatically and the section is about cable state, not Cable Detective software updates.

Live cable monitoring - Verdicts refresh the moment a cable is plugged in, unplugged, or renegotiates power. No polling, no flicker, no software updates pinging.

10 cable problems this app actually solves.

Every one of these is a real pain point people post about. Cable Detective tells you which side - the cable, the charger, the device, or the port - is the cause. No guessing.

  1. "My MacBook is charging way slower than it should." The label says 96 W, the Mac says 30 W. Cable Detective shows the negotiated USB-PD contract, every PDO the charger advertised, and whether the cable's e-marker rating is the bottleneck (un-e-markered cables cap at 60 W).
  2. "I plugged in an external display and got nothing." Some USB-C cables carry data only and no DisplayPort lanes. Cable Detective shows whether DP-Alt Mode is active, how many lanes are running, at what link rate (RBR/HBR/HBR2/HBR3/UHBR), and how many display sinks the controller sees.
  3. "My USB-C SSD is writing at 40 MB/s instead of 1 GB/s." The cable says SuperSpeed on the box but the link is running USB 2. Cable Detective shows active vs supported transports for that exact port, so you know whether the cable, the enclosure, or the host downgraded the link.
  4. "Is this cable counterfeit?" Real USB-C accessories carry a PD e-marker chip with a USB-IF vendor ID. Cable Detective decodes the SOP / SOP' / SOP" identity, shows the vendor against the official USB-IF database, and tells you if the cable simply has no e-marker (very common, not necessarily fake, but caps power at 60 W).
  5. "My Thunderbolt dock isn't running at full speed." Thunderbolt 4 vs USB4 vs USB-C 3.x are easy to confuse. Cable Detective shows the actual Thunderbolt link speed for that port and whether the dock negotiated TB or fell back to USB-C.
  6. "Cable Detective said 'liquid detected' before macOS even popped a warning." The USB-C controller exposes a Liquid Detection (LDCM) signal long before the system-level dialog appears. We surface it directly so you can stop charging before damage spreads.
  7. "This cable works in port 1 but not port 4." Different USB-C ports on the same Mac can have different controller chips and capabilities. Cable Detective shows you the per-port active and supported transport list, the controller chip, the firmware revision, and the plug event count - so you can see when a port has been physically damaged.
  8. "My Anker hub disappeared from the system." When a hub is connected the Mac sees one USB topology root and many devices behind it. Cable Detective lists every device attached behind the hub, in physical port order, with vendor IDs and class info - so you know whether the hub itself is gone or just one downstream device.
  9. "I'm travelling and want to know if this random charger is really 100 W." Cable Detective shows the charger's full PDO menu (every voltage / amperage offer it advertises), the rated maximum, and the watts you are actually pulling right now. If a no-name charger only advertises 5 V / 3 A, you'll know before you trust it overnight.
  10. "I have a drawer full of identical-looking USB-C cables. Which one is which?" Plug each cable in for a few seconds. Cable Detective reads the e-marker chip (when present) and shows the vendor (decoded against the USB-IF database), product ID, declared speed class, current capability and EPR support. For cables with no e-marker chip - very common - it shows what the cable actually negotiates with your Mac, so you can tell a real SuperSpeed or Thunderbolt cable apart from a charge-only USB 2 cable by behaviour, not by squinting at moulded plug colours.

Zero network. Not a slogan.

Cable Detective has no network entitlement. There is no server. No account. No telemetry. No analytics SDK. No crash reporting. The optional AI explanations run on Apple's on-device Foundation Models on your Mac.

If we wanted to phone home, we would need to ship a new build with new entitlements. We don't.

Read the full Privacy Policy

Requirements

Mac
Apple Silicon (M-series). Intel Macs not supported.
macOS
26 (Tahoe) or later.
AI feature
Optional. Requires Apple Intelligence enabled in System Settings.
Permissions
USB device entitlement. No file access, no network, no camera, no microphone.

Pricing

€9.99
one-time. No subscription.
  • Lifetime use of the version you bought.
  • No account. No cloud. No telemetry.
  • Family Sharing supported via Mac App Store.
  • Source: closed. Distribution: Mac App Store.
Coming soon to the Mac App Store

Submission in progress. Sign up for an email when it ships:
[email protected]

Common questions

Why does my "USB-C" port only do USB 2.0?
Because the cable, the host port, or the device chose to. Cable Detective tells you which one. SuperSpeed needs a SuperSpeed-capable cable on a SuperSpeed-capable port — many bundled cables are USB 2.0 only.
It says my charger is delivering 86 W. The label says 96 W. Bug?
No. 86 W is the negotiated USB-PD contract right now (laptop's request × charger's offer × cable rating). The charger's capability is on the box; the negotiated contract is what's actually flowing.
Can it tell me if my cable is fake?
It can tell you what the cable's e-marker chip claims (or that it has none). It cannot test the conductor quality. A cable that lies in its e-marker is rare; a cable with no e-marker chip at all is common and limits negotiated wattage to 60 W.
Does it work on Intel Macs?
No. Apple Silicon only.
Does the AI explanation send anything to a server?
No. It uses Apple's on-device Foundation Models. The app has no network entitlement at all.
Is there a free trial?
No. Cable Detective is a one-time €9.99 purchase on the Mac App Store. No subscription, no account, no recurring charge, no upsell. You buy it once and that version is yours for life. The Mac App Store does not support trials for paid apps, so we do not offer one - the FAQ, the screenshots on this page, and the live demos in App Store reviews are how you decide before you click buy.

Stop guessing. Plug it in.

Cable Detective ships v1.1.0 to the Mac App Store. Single one-time purchase. On-device only.

Notify me at launch