Great utility.

The only wrinkles for me are that Macs apparently don't interrogate cables when they don't have to, i.e., when the power adapter supplies <= 60W (not sure if that's a USB-C protocol or an Apple implementation limitation) and that the website copy is full of GPT-isms, which makes me suspect that some of the output might be assumed instead of empirically validated as well.

I'm using the hardware tester from Treedix in which you have to plug both ends of the cable and which tests a lot of things, I'm quite fond of it.

I have a basket with a lot of USB-c cables and without the tester I can't remember (nor guess) which one does what.

    Think about it. You need to generate a precise, calibrated, 40GHz signal, transmit it, then precisely measure the returned signal for phase, amplitude, and waveform integrity -at that speed. Oscilloscopes and logic analyzers that run at that speed, are damn expensive.

Something that keeps needing to be pointed out every thread this stuff appears on: What these tools report are not functionally different from just believing "what's on the packaging", despite the misleading marketing claims.

These tools read a chip called an "eMarker". These eMarkers are programmed to say whatever the manufacturer wants them to say - there's no requirement that the information be based in reality. Plenty of cables have eMarkers that claim "40Gbps" or whatever speeds, or support 240W PD...but absolutely cannot deliver either of those. And none of these consumer level software or hardware testers can actually test either of those claims. They can only take the cable's own claims at face value.

Resistance measurements can cursorily test claims of 240W but resistance changes with temperature which changes with current...so unless your tester puts 5 amps down the wire for 5 minutes and then tests resistance it's not a very good test. AFAIK none of the testers flow 5 amps through the cable.

Actual maximum data throughput is very hard to know. The only way to really "know" how much data can flow through a cable is with an expensive oscilloscope or cable tester. Because 80Gbps cables run at ~13GHz, at minimum you need a 26GHz scope (Nyquist–Shannon sampling theorem) or more practically a 52GHz scope. And it turns out it's really expensive to measure electrical signals 52 billion times per second. The necessary devices start at $15,000 (cable signal integrity tester) [0] on the very low end and only work for max 10Gbps USB 3.2 cables, or past $270,000 for 80Gbps USB4 cables (proper 60GHz oscilloscope) [1].

On the high end, each signal integrity test device can actually cost $1-2 million [2] where the base unit starts at $670,000 plus then spending additional money for hardware-accelerated analysis, specialized active probes, and the specific PAM-3 / USB4 compliance software packages.

0: https://www.totalphase.com/products/advanced-cable-tester-v2...

1: https://www.edn.com/12-bit-oscilloscope-operates-up-to-65-gh...

2: https://www.eevblog.com/forum/testgear/uxr1104a-infiniium-ux...

I'm curious if this also works for USB-A to USB-C. The use case: My Suburu has USB-A inputs and only allows wired Carplay. When I upgraded my iPhone and ditched Lightning, I had to try 6 different cables from my cable drawer to find one that supported data transfer.

I have so many cables I've accumulated over the years, I should either purge or at least categorize the functionality of each.

I literally spent more than an hour yesterday debugging issues with USB-C cables that I wasn't aware were charging only, and this shows up today... Better late than never, I suppose, and definitely worth my ten quid.

Is there something like this for Windows/Linux?

Small question: did anybody succeed to pay via Apple Pay?

ChromeOS firmware has a bunch of this built in - it's super cool. https://nelsonslog.wordpress.com/2026/01/05/chromebooks-iden... and https://www.reddit.com/r/UsbCHardware/comments/1pyojjd/comme... and https://chromium.googlesource.com/chromiumos/platform2/+/HEA... is where I found out about it. A lot of the clever capabilities rely on the firmware that you have. Source - having spent a while a few weeks back getting Codex to poke at this topic on my machine https://github.com/nedrichards/whatcable-linux/blob/main/doc... since framework do reuse parts of the ChromeOS Embedded Controller in their firmware.

"This is a Linux-native reimplementation inspired by darrylmorley/whatcable"

https://github.com/nedrichards/whatcable-linux

But (hazard guess) it comes with a headless CLI binary (no GUI libraries needed) so probably could be ported to Linux (easily with an LLM?)

https://github.com/darrylmorley/whatcable

There are options on Linux that you can google up (I don't know enough about any of them to endorse them by linking to one in particular).

As I understand it, Windows doesn't expose the necessary low-level hardware information for something like this to be possible.

A quick search found https://github.com/nedrichards/whatcable-linux, haven't tried it myself though

I came here to ask the same thing. I did find a Linux tool with the same name and purpose but that seems to be an entirely different codebase: https://github.com/nedrichards/whatcable-linux

I have a handful of wireless keyboards that just absolutely refuse to negotiate for charging with certain cables at all, so I'm hoping this will help me at least figure out what those keyboards are looking for in terms of cable.