480 Mbps · 60 W
Slow data, no video. Fine for a keyboard — useless for a display or fast SSD.
Reads IOKit & SMC · macOS 14+ · Apple silicon
Check what a USB-C cable can really do — on your Mac.
Cablyst reads the USB-C details macOS already knows — charging power, data speed, DisplayPort and Thunderbolt, connected devices — and explains them in plain words, per port. No more guessing why a cable charges slow or won't drive a display.
brew install --cask cablyst
Free to download. Or unlock deeper diagnostics with Cablyst Pro →
- Free tier · Pro optional
- Apple silicon · macOS 14+
- Signed & notarised
- 19 languages
The problem
Same USB-C plug. Completely different cables.
A drawer full of identical-looking USB-C cables — yet one charges a laptop at full speed and the next barely runs a keyboard; one drives a 4K display and the next carries no video at all. The connector tells you nothing, and the cable that worked last month can be the one quietly underperforming today.
USB 2.0
USB4
40 Gbps · 100 W
Fast data and strong charging. Handles most displays and external drives.
Thunderbolt 5
up to 120 Gbps · 240 W
Top speed and power, dual high-res displays — and identical to the cheap one by sight.
Ask it the way you'd ask a person
Common USB-C cable questions, answered on your Mac.
You don't need to know what an e-marker is. Plug a cable into your Mac and ask the obvious question — Cablyst answers in plain words.
“What kind of USB-C cable is this?”USB4 · 40 Gbps · 100 W
“Is this the fast one or the slow one?”Fast — not a USB 2.0 cable
“Will it charge my MacBook at full speed?”Yes — 100 W, 5 A rated
“Can this cable run my 4K monitor?”Yes — 2× 4K over DisplayPort
“Is it Thunderbolt, or just USB-C?”Thunderbolt 4
“Which look-alike cable is the good one?”This one — the other caps at 60 W
What Pro shows you
USB-C & Thunderbolt diagnostics, read from your Mac's hardware.
| Feature | What it answers | Tier |
|---|---|---|
| Power Monitor | Live per-port watts/volts/amps, history, and a front-port draw estimate. | Pro |
| Authenticity Check | Scored red-flag analysis to spot likely-counterfeit cables and chargers. | Pro |
| Display Diagnostics | Current vs. maximum resolution/refresh and the DisplayPort link carrying it. | Pro |
| PD Contract Inspector | The negotiated USB-PD contract and every offered power profile, per port. | Pro |
| Negotiation Diagnostics | What the port, cable, and device each support vs. what was negotiated. | Pro |
| Cable Diagnostics | Per-port pin map, plug orientation, e-marker and PD detail. | Pro |
| Cable History | Save a cable and track how it performs over time. | Pro |
| Cable Resistance | Estimate series resistance from voltage-sag under load. | Pro |
| Basic identity + Thunderbolt link | Cable type, vendor, connection state, TB link info. | Free |
Plus Device Log, Port Health, PD Event Trace, Liquid Detection, Raw VDO Identity.
Built for people who actually check
Which USB-C cable problem are you hitting?
Running two docks
Why is one USB-C port slower than the other?
Compare the negotiated link on each port side by side, with the weak link flagged.
Buying off a marketplace
Is this USB-C cable a counterfeit?
Read the e-marker, check USB-IF registration, and get a red-flag score.
Just spent $300 on a dock
Is my dock running at full USB-C speed?
Confirm it's running full-rate — or find out it isn't, and exactly where it caps.
A drawer full of cables
Which of my USB-C cables is actually good?
Save each one and build a library of what every cable can really do.
Worried about a spill
Did liquid get into the USB-C port?
Read the per-port liquid-detection sensor status.
The household tech support
Just tell me what this USB-C cable does
Plain-language verdicts you can screenshot and send.
Free tool
Is your USB-C cable a counterfeit?
Run the red-flags checklist — the same signals Cablyst's Authenticity Check reads from the hardware — and get a counterfeit-risk score in ten seconds.
Check a cable →vendor id0x0000 (zeroed)
usb-if registeredno
claimed vs price240 W for $3
score22 / 100