Would this tell me if a cable is close to the end of it's life? I like to travel light and I've had cables (mostly phone/pad power) go out on trips after working as expected when I packed.
I think you would need something that tracks relevant per cable metrics over time to see if it is degrading.
That one just says yes/no, but maybe yes/no starts to flicker around its end of life?
Nod - that's what I was thinking. I expect it's often the connectors that deteriorate so perhaps moving them around while plugged in would tell me. Seems like a useful tool to have around.
i've used a treedix tester like this. the edition with many led lights, not the one with a screen.
wiggle the cables around to see if and when any of the lights flicker, indicating a bad or broken connection. i've found a few bad cables that would intermittently fail.
Yep, I probably have the same one. Insanely useful, and it is also crazy how much variance there is in cables. You can’t believe what the sellers claim, so many times they end up being less capable than claimed.
> I'm using the hardware tester from $INSERT_NAME_HERE
Oh god not again... before everyone starts naming their favourite brand, here's a 265 comment HN thread[1] (from last week !) on why these cheap USB-cable "testers" are not worth anything.
TL;DR You need a six-figure wallet to seriously call anything a "hardware tester" for USB cables. User ChrisMarshallNY has a one-liner summary buried in that thread:
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.
If you only paid $40 for a black-box on your favourite online marketplace, then what you've got is definitively NOT a USB-cable tester.
Huh? Decent quality cable testers can be had for like $20,000. There's a difference between a general-purpose oscilloscope or logic analyzer and a purpose-built domain-specific appliance. I probably could've saved up for one in just a few months back when I had a job earlier this year.
> Decent quality cable testers can be had for like $20,000.
See the discusison linked to.
Trust me, my interest was piqued by that thread and I went down the rabbit warren with Mr Google and spent far too much time on the subject. I looked at the various manufacturers and the setups required.
TL;DR: To start with, you need fancy harness assemblies. Then you need to plug those harnesses into very, very expensive equipment.
You're not going to find anything for $20k. High-throughput USB-cable testing simply can't be done the same way copper CAT6 certification can with a 20k Fluke.
For those who want to play with Mr Google, some manufacturers from my notes: Wilder Technologies, Allion, Keysight, Tektronix, Teledyne LeCroy
In the world of specialized test equipment, $20k isn't too bad at all. It's a certainly still a lot of money in absolutes, but the barrier to entry is simple very high for this class of kit. The sales volume is low and the engineering to do precise work with RF signals at these kinds of frequencies is complex. The people doing the work of designing, building, and getting this stuff into the hands of end-users still need enough money to live healthy lives.
And $20,000 is five figures, so an off-the-cuff six figure estimate is an error of an order of magnitude. That's quite a large error.
But to bring it all back 'round again: The oft-repeated suggestion that a $40 device can do the same job represents an error of 3 or more orders of magnitude. :)
Some of the stuff in this cheaper class of kit can observe what happens in terms of voltage and/or current on the wire between two devices, some of them can have a chat with a cable and/or a device on their own to see what they state of their capabilities (as this software does), and some of them can also test things like DC continuity. That's useful, but it doesn't help to grade the actual signal characteristics of the cable.
There's a galaxy of difference between DC and a 40 GHz symbol rate.
Are you suggesting there is no middle ground and that simply knowing if a USB-C cable is a USB C cable or a fake one can't be done with a cheap tester?
Buying my cables from decent manufacturers does not tell me what specific version of USB a cable purports to support, what voltage of USB-PD it can transmit, whether or not it can do Thunderbolt or DisplayPort, or a dozen other random capabilities inherent in these cables.
I’ll be honest, man, it seems like you are not engaging in this discussion in good faith. You are hell-bent on pushing this viewpoint while completely ignoring what others are telling you their actual needs are.
We get it. A cheap tester will not tell me if a cable from a dodgy supplier is counterfeit. It will tell me what the capabilities are of the dozens of assorted cables I own from reputable manufacturers, which is otherwise difficult if not impossible to discern.
What the chip reports is itself inherently useful information, especially if you have cables from reliable manufacturers.
There are people here actively using the term "it verifies" in relation to their $40 toy they bought on Amazon, they absolutely need to be corrected firmly.
A $40 toy DOES NOT "verify" anything it (a) Does a DC continuity test (b) Reads the chips on the cable. NOTHING ELSE.
People here trying to pretend it does more than a+b need a reality check.
Am I missing something? For practical use you only care if it carries a certain amount of packets per second without excessive retries, not whether it preserves the waveform exactly.
> For practical use you only care if it carries a certain amount of packets per second without excessive retries
The $40 black-boxes do two things:
1. Basic electrical continuity test
2. Read the marker chips (if present)
There is zero chance that a $40 black-box, even if it did a naïve packet pushing test, would deliver you reproducible results and introduces all sorts of other random variables.
"Excessive retries" sounds like exactly the sort of intermittent, hard-to-diagnose cable issues that you will not find unless you test the USB cable on a 6-figure rig. :)
OK sure your 6 figures thing or even that 20k thing are way better testers than the Treedix. But for my use case, i.e. verify what's actually in the cable (not blindly trusting the marker) the latter is sufficient and very ergonomic, and the "real" testers are overkill.
> verify what's actually in the cable (not blindly trusting the marker) the latter is sufficient
But as was repeated 101 times on that thread ....
All that those cheap $40 boxes are doing IS reading the marker.
Sadly you are kidding yourself if you think a $40 box off Amazon is doing any sort of "verification". Let alone in any sort of calibrated, reproducible sense free of random unknown variables.
If I want to tell a cable that can do only USB 2 from one that can do 3 from one that is actually thunderbolt, the treedix is a godsend. So. Many. Devices. Come with some unknown usb cable. Can it only charge? Transfer data? How fast? Stuff like signal integrity, dispersion, differential timing, phase shift etc are totally out of scope for this simple thing - telling apart these cables.
You're arguing that the ability to read a label is absolutely worthless, because they might occasionally lie to you. It's not so absolute.
Maybe you need absolutely 100% confidence your labels don't lie, but I and presumably others on this thread merely want to check for the presence of the label and the declarations on it. That's enough for me to sort my cables.
Maybe occasionally I'll come across a counterfeit cable (or more likely, a damaged cable, because I generally buy reputable ones) and have one underperform its label, but I can get rid of it then.
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 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.
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 used to use one for Android. It worked for about 6 weeks, then stopped working, then a few months later I tried it and it worked for about 6 weeks before stopping working again!
For cheap cables like USB-A to USB-C, I just throw away all cables that do not support data transfer. I don’t need the mental overhead of categorizing these cables. So any USB-A to USB-C cable in my cable drawer would work in this scenario. And CarPlay doesn’t even require USB 3.0; 2.0 is enough.
Your Subaru+iPhone combo already tests that capability, does it not?
Just purge the known-bad cables already. :) (Gather them up and scrap them if the landfill seems like a harsh destination.)
In a situation of surplus, there's no reason I can think of where keeping charging-only cables around has merit.
Later on, if you need a cable that very specifically can do USB 3 speeds, then: Use a flashlight and look inside of the USB A connector. The ones that only have 1 row of 4 contacts will never be able to do USB 3, while the ones with 2 rows contacts will probably work fine.
I don't trust a random, in-the-wild USB port to provide sane power, so I bring my own charging stuff. :)
That said: My travel tends to happen with my own car, and that travel is never international. I can see how a charge-only cable would be beneficial for others.
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.
If you can afford it, I'd honestly throw these out. "Charging only" is not a spec-compliant thing in USB-C, and personally I wouldn't want to re-discover which devices do and don't support them every time I just want to quickly grab a cable.
What's less easy to replace are all these damn USB-C devices lacking the UFP-identifying circuitry that only work on USB-A chargers using A-to-C cables...
To be clear, they're not literally "charging only", AIUI they're spec-compliant cables with USB2.0 480Mbps and power delivery, and they're allowed to not have the four SuperSpeed wire pairs. They're still useful for low bandwidth devices (like charging my keyboard/mouse).
Incidentally — I spent an inordinate amount of time searching for USB3.2 cables on Amazon, and the vast majority of cables were actually just USB2.0 cables with PD support, and not actual Full-Featured cables.
Ah, I love these as they're generally much thinner/lighter/more flexible than USB-C 3 cables but still support at least 60W power delivery! Advertising them as USB 3 is a shame, though.
Amazon's search is awful and I do not recall a time when it was better. It's probably this way by design, so that it always tends to present a never-ending stream of products to buy.
But over here in the real world where I need a specific sort of USB 3.2 widget: Either the USB 3.2 widget exists, or it does not exist. Presenting pages and pages of not-results that were already explicitly defined as irrelevant do not help a person to spend money. :)
(eBay's advanced search mode seems to still get it close-enough to right when rote specificity is important. I use it all the time to find very particular things.)
I would recommend getting one of the small cable testers, like the one from Treedix. Gives you all sorts of information very quickly, including resistance levels and capabilities.
I was trying to figure out slow network speeds one day and I finally swapped an ethernet cable and got full speed.
It turns out some ethernet cables are missing wires - and capped at 100Mbps! Wait what? I didn't even know that was a thing. I don't know where I got the wire, but into the trash it goes.
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.
While I totally agree if you want to truly know the quality of the signal you need a very expensive box to actually measure the tiny deviations, if the question is "can this thing handle 80Gbit of data", can't you just get a couple of USB4 chips or whatever and have one send a pattern at that throughput and have the other try and receive and confirm that pattern? That would give you a basic "yes/no" kind of answer of "can it send XGbit?" I agree the processing capacity for such a thing at retail isn't likely to be $40, but probably a good bit less than >$15k. After all, you can get <$1,000 laptops that can do that pretty easily.
For example, I don't need to precisely measure exactly how messed up the signal is to know if the HDMI cable works or not at a given resolution. I'll see the TV have issues displaying a picture. Either the picture is there reliably or its not. I'm not trying to fine tune the cable, I'm just trying to see if it generally works or not.
As for testing power delivery, its not that electrically complicated to put a few amps through a wire for a few minutes. That said, the user must be aware if the cable isn't up to the standards that the chip states you could have some serious issues on your hands, but I guess better to find out on the tester at the workbench or desk than at your bedside.
> 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.
Couldn't you just do a data transfer test over the cable and check the error rate? At least in theory, the controller might not report enough I guess.
If you are just wanting "to use it", sure.
If you are building a cable for a specific purpose, or want to actually ensure that it will work, use test equipment.
Isn't that what most people here are really wanting? I don't imagine most people here are seriously wanting to know the exact extreme measurements, just "can this cable reasonably do what I need from it? Does it do what it claims on the label generally?"
People don't want "reasonably do". They want "resolutely do".
They don't say it like that, but: They sure do get grumpy when the Thunderbolt-connected display for their laptop shits the bed mid-afternoon on a Wednesday after a year, or the export for their recording session fails on a device they've done this with dozens of times before, or the cable connecting the camera they use to watch their cats no longer works: They get quite grumpy about these things, indeed.
So they want resoluteness, not reasonableness.
I know it's 2026 and many of us are used to using bots that are compulsively high-confidence liars.
But just go ahead and try to reason with someone about a local computer that fails tasks apparently-randomly. That's the makings of a bad scene. :)
I'm just meaning people here are looking for a "does it work", a binary yes/no. Not a precise measurement of exactly how perfectly the digital signal is making it through the wire. They don't care exactly what the SNR is or whatever, they just want to know when they plug in the cable for a given need will this cable work?
You don't need a six figure oscilloscope or logic analyzer to know "does it work".
They can determine that today without extra parts or test equipment at all: They plug the cable in to the equipment they already have, and it either works in the way they care about or it does not.
If that's the extent of the thing that they want to do, then there is nothing further to discuss: They already have everything they need to begin that kind of evaluation immediately.
It doesn't give them any viable forecast as to whether the cable will work or not with some other bits of gear, though, or on some other day. It just evaluates it as a binary pass/fail for right now.
"Digital" cables are often dismissed as simple things, wherein: A string of bits goes in one end of a random collection of copper wires or metal coat hangers or whatevers, and it always comes out the other end the same way. After all, it's digital.
But reality isn't that way at all, and there's a lot that goes into a reliable cable that connects things together. Characteristic impedance is only one of the things[1].
---
Interrogating the emarker doesn't provide further practical information, either. The information that can come from there is similar to what wording on the package on the shelf at the store is: Both things merely document what someone else once said about what the cable should be capable of doing.
Like a printed URL vs a QR code that each lead to the same web site: It's the same information, differing only in presentation. One of these presentations is human readable and other is not.
And neither thing neither thing tells the user whether that website is still reachable or whether it fell off the face of the earth, or whether it is friendly or evil.
It's all just a fixed string of information and that information can be wrong. It can even be deliberately wrong. The words on the box, the bits burned into the emarker chip, the URL, and the QR code: In the best case, they may or may not lead to a useful outcome.
In the worst case, they can be lies.
emarker chips set a hard not-to-exceed performance limit, but they don't provide a promise of performance below that limit.
---
[1]: Like the RG-6 cable connecting a cable modem to the wall: It functions with a very specific characteristic impedance of 75 Ohms. Or the SATA cable in the desktop computer of someone with some Linux ISOs: That's twinaxial cable, with its center pair of straight, parallel wires and the shielding all interacting with eachother at a controlled impedance. USB 4, meanwhile, uses cables with a characteristic impedance of 90 Ohms.
Characteristic impedance can be complex, and even dynamic. Like the ye olde POTS phone lines, for voice audio: That was designed and built very specifically in order to behave itself within those seemingly-minor constraints. 600 Ohms at 1 KHz was the target, and that was good enough for a very long time. But when frequencies increase into the MHz range with things like DSL, that characteristic impedance tends to drop to somewhere in the realm of 100 Ohms.
100 Ohms is, not coincidentally, around the same characteristic impedance that our Ethernet cables seek to provide at the frequencies we care about in that space. :)
Whatever that characteristic impedance is (at whatever frequencies are being used), when it matches what the termination impedance of the two endpoints are then we get an ideal transmission line. (That's always the target; an ideal transmission line is a glorious thing, indeed.)
But bad impedance match results in not just seemingly-obvious things like attenuation; it also introduces things like reflection -- signals bouncing back and forth, causing temporal distortions that obscure the desired signal. Bad matches also result in standing wave patterns where the length of the wire makes a difference, but shorter isn't better: The pattern of these standing waves within a wire are a function of the wavelength of the signal, not the overall length of the cable.
It's easy to make any of those things work within their designed uses and designated systems, where all of the effort to get this stuff right happens behind the scenes.
It's much harder to replace with bits of copper wire from the junk drawer and get reliably-good results.
For 1KHz in modern-ish POTS lines, that wavelength is around 40km. That's easy-enough to hand-wave away for lots of uses. The impedance matching can all be completely screwed and it really doesn't matter much for short runs.
But at 12.8GHz (the frequency maximum of USB 4) in a USB cable, the wavelength is only around 16mm. It's kind of a big deal to seek to have the little parts exactly-right in these seemingly-innocuous, hard-to-see ways. :)
And the impedance changes in-use, too. A kink in the wire produces an impedance aberration at that point that can be measured, and that can also be bad enough to produce practical issues that affect real-world performance.
Bad enough to fail the binary test you described today, even though the test was completely successful yesterday.
I'm a ham and took a number of EE/electromagnetism classes in college, so I totally understand what you're talking about with wire characteristics. I agree there's a ton of hidden complexity on these high bandwidth cables we can buy in the discount bin at electronics store.
> They plug the cable in to the equipment they already have, and it either works in the way they care about or it does not.
That's the thing though, I don't always have these things handy or ready to just plug something in quick and test. I'd like some kind of small device which can actually do some quick tests and see if it passes or fails at whatever power and bitrate more than just what the little identifier says it can do. Because, I agree, you can't trust the tag, there's a lot going on. And a cable that tested fine a year ago might be too messed up to work today.
In the end, it's also sometimes messy testing bandwidth given two random devices. Are they just being buggy with their handshake? Are we getting strange driver issues? Something else going on? A more dedicated tester tool can just be sure these two things definitely, without question should work just fine at whatever bandwidth they're trying to test with. And with a button press it does it and clearly gives the results. If it's not too expensive and you end up handling lots of questionable cables, sounds kind of nice!
> And the impedance changes in-use, too. A kink in the wire produces an impedance aberration at that point that can be measured, and that can also be bad enough to produce practical issues that affect real-world performance.
This is still true of a six figure oscilloscope testing the wire. If you're not manipulating the wire in realistic ways your super expensive tool isn't really going to answer that any more as the cheaper pass/fail. What might look just fine on the scope may look really bad when you bend it wrong or it gets a little internal crack or too much outside interference or something. You'll potentially be clued in to it being closer to being a messed up signal, but not necessarily.
It's just like ethernet networks in this way: We can examine a cable and see if it works by plugging in some regular gear with it, and look at the success/error rate. Lots of people do this. It's an empirical way to see if a cable is good enough today, under present conditions, as a binary pass/fail state.
Or: We can examine a cable using specialized gear to characterize its performance, and then: We measure not just if the cable is good enough for today, but how close it is to the edge of acceptance it is. This allows a fantastic cable that is exceptionally excellent to be discerned from the ones that may be merely good-enough-under-present-conditions edge-cases.
From there, it may in fact be sane to suggest that the better-performing cable is likely to have better longevity as it inevitably degrades from human factors like...using the thing.
So basically, it's cheap for them to defraud the consumer, and prohibitively expensive for the consumer to adequately protect themselves from it. The absolute state.
For people who cannot, or do not want to spend fantastic amounts of money on cable testers, can you name any reliable cable brands that, generally or strictly, sell cables which match their marketing material?
I don't need absolute perfection, but I hate the idea of buying an expensive cable, and being lied to about how good the performance is. I don't mind paying more for quality, but its hard for me to really articulate any difference between two USB cables, except by maybe their length, and how "sturdy" one might feel compared to the other.
It wouldn't do a lot to solve the issue of various low quality cables I already own, but I wouldn't mind throwing money at a cable company that doesn't lie to its customers.
At that price they’re my default “generic” cable. Unless I need a longer length or 80Gbps this is the main workhorse in my home. It’s nice just never worrying about discerning “charging” cable from “data” cable.
CableMatters is a very reputable brand if you need more variety in selection. Monoprice also seems to care about quality. CalDigit and Apple both have vested interest in providing quality cables. Strong brand is a good starting point, but even then I still try to stick with USB-IF certified offerings only.
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.
Nice. You just got them a sale from me. I have a crap ton of cables so this will come in handy.
Exactly my use case.
And I have nothing to gain from that sale.
Would this tell me if a cable is close to the end of it's life? I like to travel light and I've had cables (mostly phone/pad power) go out on trips after working as expected when I packed.
I think you would need something that tracks relevant per cable metrics over time to see if it is degrading. That one just says yes/no, but maybe yes/no starts to flicker around its end of life?
Nod - that's what I was thinking. I expect it's often the connectors that deteriorate so perhaps moving them around while plugged in would tell me. Seems like a useful tool to have around.
i've used a treedix tester like this. the edition with many led lights, not the one with a screen.
wiggle the cables around to see if and when any of the lights flicker, indicating a bad or broken connection. i've found a few bad cables that would intermittently fail.
That's great. Thank you for the feedback - I ordered one just now.
Looks like the paid/pro version does this.
> Cable history
> Add a cable, give it a name, and WhatCable records how it performs over time, with a verdict per cable.
Yep, I probably have the same one. Insanely useful, and it is also crazy how much variance there is in cables. You can’t believe what the sellers claim, so many times they end up being less capable than claimed.
> I'm using the hardware tester from $INSERT_NAME_HERE
Oh god not again... before everyone starts naming their favourite brand, here's a 265 comment HN thread[1] (from last week !) on why these cheap USB-cable "testers" are not worth anything.
TL;DR You need a six-figure wallet to seriously call anything a "hardware tester" for USB cables. User ChrisMarshallNY has a one-liner summary buried in that thread:
If you only paid $40 for a black-box on your favourite online marketplace, then what you've got is definitively NOT a USB-cable tester.
[1] https://news.ycombinator.com/item?id=49152255
Huh? Decent quality cable testers can be had for like $20,000. There's a difference between a general-purpose oscilloscope or logic analyzer and a purpose-built domain-specific appliance. I probably could've saved up for one in just a few months back when I had a job earlier this year.
> Decent quality cable testers can be had for like $20,000.
See the discusison linked to.
Trust me, my interest was piqued by that thread and I went down the rabbit warren with Mr Google and spent far too much time on the subject. I looked at the various manufacturers and the setups required.
TL;DR: To start with, you need fancy harness assemblies. Then you need to plug those harnesses into very, very expensive equipment.
You're not going to find anything for $20k. High-throughput USB-cable testing simply can't be done the same way copper CAT6 certification can with a 20k Fluke.
For those who want to play with Mr Google, some manufacturers from my notes: Wilder Technologies, Allion, Keysight, Tektronix, Teledyne LeCroy
Here's one blog post I uncovered during my researches: https://www.keysight.com/blogs/en/tech/bench/2023/02/17/powe...
Aren't you both agreeing.. that it is way beyond $40? :)
You need a six figure wallet to want to spend $20k on a tester :)
> You need a six figure wallet to want to spend $20k on a tester :)
Heh. I'll give you a +1 for that one.
Reminded me of the old joke...
What's the quickest way to become a millionaire ? Be a billionaire and buy an airline.
In the world of specialized test equipment, $20k isn't too bad at all. It's a certainly still a lot of money in absolutes, but the barrier to entry is simple very high for this class of kit. The sales volume is low and the engineering to do precise work with RF signals at these kinds of frequencies is complex. The people doing the work of designing, building, and getting this stuff into the hands of end-users still need enough money to live healthy lives.
And $20,000 is five figures, so an off-the-cuff six figure estimate is an error of an order of magnitude. That's quite a large error.
But to bring it all back 'round again: The oft-repeated suggestion that a $40 device can do the same job represents an error of 3 or more orders of magnitude. :)
Some of the stuff in this cheaper class of kit can observe what happens in terms of voltage and/or current on the wire between two devices, some of them can have a chat with a cable and/or a device on their own to see what they state of their capabilities (as this software does), and some of them can also test things like DC continuity. That's useful, but it doesn't help to grade the actual signal characteristics of the cable.
There's a galaxy of difference between DC and a 40 GHz symbol rate.
Are you suggesting there is no middle ground and that simply knowing if a USB-C cable is a USB C cable or a fake one can't be done with a cheap tester?
> Are you suggesting there is no middle ground
Sadly yes.
Like many people on that thread concluded:
The best "middle ground" thing you can do is pay a premium to buy your cables from reputable manufacturers.
Buying my cables from decent manufacturers does not tell me what specific version of USB a cable purports to support, what voltage of USB-PD it can transmit, whether or not it can do Thunderbolt or DisplayPort, or a dozen other random capabilities inherent in these cables.
> Buying my cables from decent manufacturers does not tell me what specific version of USB a cable purports to support
A $40 toy won't tell you if the marker chips it has just read are fake / counterfeit.
You need the expensive kit for that.
I’ll be honest, man, it seems like you are not engaging in this discussion in good faith. You are hell-bent on pushing this viewpoint while completely ignoring what others are telling you their actual needs are.
We get it. A cheap tester will not tell me if a cable from a dodgy supplier is counterfeit. It will tell me what the capabilities are of the dozens of assorted cables I own from reputable manufacturers, which is otherwise difficult if not impossible to discern.
What the chip reports is itself inherently useful information, especially if you have cables from reliable manufacturers.
> You are hell-bent on pushing this viewpoint
Its not a viewpoint "man", it is a FACT.
There are people here actively using the term "it verifies" in relation to their $40 toy they bought on Amazon, they absolutely need to be corrected firmly.
A $40 toy DOES NOT "verify" anything it (a) Does a DC continuity test (b) Reads the chips on the cable. NOTHING ELSE.
People here trying to pretend it does more than a+b need a reality check.
Am I missing something? For practical use you only care if it carries a certain amount of packets per second without excessive retries, not whether it preserves the waveform exactly.
> For practical use you only care if it carries a certain amount of packets per second without excessive retries
The $40 black-boxes do two things:
There is zero chance that a $40 black-box, even if it did a naïve packet pushing test, would deliver you reproducible results and introduces all sorts of other random variables.
"Excessive retries" sounds like exactly the sort of intermittent, hard-to-diagnose cable issues that you will not find unless you test the USB cable on a 6-figure rig. :)
OK sure your 6 figures thing or even that 20k thing are way better testers than the Treedix. But for my use case, i.e. verify what's actually in the cable (not blindly trusting the marker) the latter is sufficient and very ergonomic, and the "real" testers are overkill.
> verify what's actually in the cable (not blindly trusting the marker) the latter is sufficient
But as was repeated 101 times on that thread ....
All that those cheap $40 boxes are doing IS reading the marker.
Sadly you are kidding yourself if you think a $40 box off Amazon is doing any sort of "verification". Let alone in any sort of calibrated, reproducible sense free of random unknown variables.
Then I am kidding myself, because I'm convinced it does a lot more.
> Then I am kidding myself, because I'm convinced it does a lot more.
Good luck spotting those counterfeit / phony markers with your $40 toy.
Just one of many examples of basic things your $40 toy won't tell you.
Man you're missing the mark.
If I want to tell a cable that can do only USB 2 from one that can do 3 from one that is actually thunderbolt, the treedix is a godsend. So. Many. Devices. Come with some unknown usb cable. Can it only charge? Transfer data? How fast? Stuff like signal integrity, dispersion, differential timing, phase shift etc are totally out of scope for this simple thing - telling apart these cables.
> If I want to tell a cable that can do only USB 2 from one that can do 3 from one that is actually thunderbolt
And if the marker chips in your "some unknown usb cable" are fake / counterfeit ? Then what ?
Your $40 toy won't help with that scenario and you will be back at square one. That's what.
You're arguing that the ability to read a label is absolutely worthless, because they might occasionally lie to you. It's not so absolute.
Maybe you need absolutely 100% confidence your labels don't lie, but I and presumably others on this thread merely want to check for the presence of the label and the declarations on it. That's enough for me to sort my cables.
Maybe occasionally I'll come across a counterfeit cable (or more likely, a damaged cable, because I generally buy reputable ones) and have one underperform its label, but I can get rid of it then.
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.
What would be really interesting is if I could connect a cable to two ports on a Mac and have the Mac test the cable.
> What would be really interesting is if I could connect a cable to two ports on a Mac and have the Mac test the cable.
Not reproducible and introduces all sorts of other random variables to your test (buffering etc.).
Is there something like this for Windows/Linux?
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.
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.
"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 is also https://github.com/Zetaphor/whatcable-linux (if you want a KDE UI rather than Gnome) and https://github.com/vzaliva/whatcable-linux-cli (a fork of the KDE repo, but only leaves the CLI tool).
WhatKable was right there!
A quick search found https://github.com/nedrichards/whatcable-linux, haven't tried it myself though
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.
Check this for more details on Windows (original author's repo) https://github.com/darrylmorley/whatcable-windows
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.
This adapter works with my Android phone and makes my Android Auto wireless: https://aliexpress.com/item/1005008214786824.html
But it is the second product I tried; the first one didn't work (it's a 2020 Stellantis car). So, YMMV.
I'd recommend a wireless CarPlay adapter. I bought one for my car, and it's a game-changer.
I used to use one for Android. It worked for about 6 weeks, then stopped working, then a few months later I tried it and it worked for about 6 weeks before stopping working again!
I see other folks provided options, in case you want to avoid aliexpress, this one worked for me for the past 4 years
https://a.co/d/0d9EOGRW
Does require a bit of setup, can scan reviews to see if people have optimized a config for your specific vehicle
For cheap cables like USB-A to USB-C, I just throw away all cables that do not support data transfer. I don’t need the mental overhead of categorizing these cables. So any USB-A to USB-C cable in my cable drawer would work in this scenario. And CarPlay doesn’t even require USB 3.0; 2.0 is enough.
Your Subaru+iPhone combo already tests that capability, does it not?
Just purge the known-bad cables already. :) (Gather them up and scrap them if the landfill seems like a harsh destination.)
In a situation of surplus, there's no reason I can think of where keeping charging-only cables around has merit.
Later on, if you need a cable that very specifically can do USB 3 speeds, then: Use a flashlight and look inside of the USB A connector. The ones that only have 1 row of 4 contacts will never be able to do USB 3, while the ones with 2 rows contacts will probably work fine.
I keep charge only cables for traveling. I don't trust the USB port in whatever I'm connecting to so the power only cable comes out.
I don't trust a random, in-the-wild USB port to provide sane power, so I bring my own charging stuff. :)
That said: My travel tends to happen with my own car, and that travel is never international. I can see how a charge-only cable would be beneficial for others.
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.
If you can afford it, I'd honestly throw these out. "Charging only" is not a spec-compliant thing in USB-C, and personally I wouldn't want to re-discover which devices do and don't support them every time I just want to quickly grab a cable.
What's less easy to replace are all these damn USB-C devices lacking the UFP-identifying circuitry that only work on USB-A chargers using A-to-C cables...
To be clear, they're not literally "charging only", AIUI they're spec-compliant cables with USB2.0 480Mbps and power delivery, and they're allowed to not have the four SuperSpeed wire pairs. They're still useful for low bandwidth devices (like charging my keyboard/mouse).
Incidentally — I spent an inordinate amount of time searching for USB3.2 cables on Amazon, and the vast majority of cables were actually just USB2.0 cables with PD support, and not actual Full-Featured cables.
Ah, I love these as they're generally much thinner/lighter/more flexible than USB-C 3 cables but still support at least 60W power delivery! Advertising them as USB 3 is a shame, though.
Amazon's search is awful and I do not recall a time when it was better. It's probably this way by design, so that it always tends to present a never-ending stream of products to buy.
But over here in the real world where I need a specific sort of USB 3.2 widget: Either the USB 3.2 widget exists, or it does not exist. Presenting pages and pages of not-results that were already explicitly defined as irrelevant do not help a person to spend money. :)
(eBay's advanced search mode seems to still get it close-enough to right when rote specificity is important. I use it all the time to find very particular things.)
I would recommend getting one of the small cable testers, like the one from Treedix. Gives you all sorts of information very quickly, including resistance levels and capabilities.
I was trying to figure out slow network speeds one day and I finally swapped an ethernet cable and got full speed.
It turns out some ethernet cables are missing wires - and capped at 100Mbps! Wait what? I didn't even know that was a thing. I don't know where I got the wire, but into the trash it goes.
100 Mbps is sometimes just enough for the job. And it’s easy to see that you only have two pairs instead of four – just look at the connector.
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...
While I totally agree if you want to truly know the quality of the signal you need a very expensive box to actually measure the tiny deviations, if the question is "can this thing handle 80Gbit of data", can't you just get a couple of USB4 chips or whatever and have one send a pattern at that throughput and have the other try and receive and confirm that pattern? That would give you a basic "yes/no" kind of answer of "can it send XGbit?" I agree the processing capacity for such a thing at retail isn't likely to be $40, but probably a good bit less than >$15k. After all, you can get <$1,000 laptops that can do that pretty easily.
For example, I don't need to precisely measure exactly how messed up the signal is to know if the HDMI cable works or not at a given resolution. I'll see the TV have issues displaying a picture. Either the picture is there reliably or its not. I'm not trying to fine tune the cable, I'm just trying to see if it generally works or not.
As for testing power delivery, its not that electrically complicated to put a few amps through a wire for a few minutes. That said, the user must be aware if the cable isn't up to the standards that the chip states you could have some serious issues on your hands, but I guess better to find out on the tester at the workbench or desk than at your bedside.
Sure. But the cable tester that you describe here doesn't exist. You could maybe DIY it but there's none off the shelf.
> 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.
Couldn't you just do a data transfer test over the cable and check the error rate? At least in theory, the controller might not report enough I guess.
If you are just wanting "to use it", sure. If you are building a cable for a specific purpose, or want to actually ensure that it will work, use test equipment.
IT interconnect closet vs. air vehicle.
> If you are just wanting "to use it", sure.
Isn't that what most people here are really wanting? I don't imagine most people here are seriously wanting to know the exact extreme measurements, just "can this cable reasonably do what I need from it? Does it do what it claims on the label generally?"
People don't want "reasonably do". They want "resolutely do".
They don't say it like that, but: They sure do get grumpy when the Thunderbolt-connected display for their laptop shits the bed mid-afternoon on a Wednesday after a year, or the export for their recording session fails on a device they've done this with dozens of times before, or the cable connecting the camera they use to watch their cats no longer works: They get quite grumpy about these things, indeed.
So they want resoluteness, not reasonableness.
I know it's 2026 and many of us are used to using bots that are compulsively high-confidence liars.
But just go ahead and try to reason with someone about a local computer that fails tasks apparently-randomly. That's the makings of a bad scene. :)
I'm just meaning people here are looking for a "does it work", a binary yes/no. Not a precise measurement of exactly how perfectly the digital signal is making it through the wire. They don't care exactly what the SNR is or whatever, they just want to know when they plug in the cable for a given need will this cable work?
You don't need a six figure oscilloscope or logic analyzer to know "does it work".
They can determine that today without extra parts or test equipment at all: They plug the cable in to the equipment they already have, and it either works in the way they care about or it does not.
If that's the extent of the thing that they want to do, then there is nothing further to discuss: They already have everything they need to begin that kind of evaluation immediately.
It doesn't give them any viable forecast as to whether the cable will work or not with some other bits of gear, though, or on some other day. It just evaluates it as a binary pass/fail for right now.
"Digital" cables are often dismissed as simple things, wherein: A string of bits goes in one end of a random collection of copper wires or metal coat hangers or whatevers, and it always comes out the other end the same way. After all, it's digital.
But reality isn't that way at all, and there's a lot that goes into a reliable cable that connects things together. Characteristic impedance is only one of the things[1].
---
Interrogating the emarker doesn't provide further practical information, either. The information that can come from there is similar to what wording on the package on the shelf at the store is: Both things merely document what someone else once said about what the cable should be capable of doing.
Like a printed URL vs a QR code that each lead to the same web site: It's the same information, differing only in presentation. One of these presentations is human readable and other is not.
And neither thing neither thing tells the user whether that website is still reachable or whether it fell off the face of the earth, or whether it is friendly or evil.
It's all just a fixed string of information and that information can be wrong. It can even be deliberately wrong. The words on the box, the bits burned into the emarker chip, the URL, and the QR code: In the best case, they may or may not lead to a useful outcome.
In the worst case, they can be lies.
emarker chips set a hard not-to-exceed performance limit, but they don't provide a promise of performance below that limit.
---
[1]: Like the RG-6 cable connecting a cable modem to the wall: It functions with a very specific characteristic impedance of 75 Ohms. Or the SATA cable in the desktop computer of someone with some Linux ISOs: That's twinaxial cable, with its center pair of straight, parallel wires and the shielding all interacting with eachother at a controlled impedance. USB 4, meanwhile, uses cables with a characteristic impedance of 90 Ohms.
Characteristic impedance can be complex, and even dynamic. Like the ye olde POTS phone lines, for voice audio: That was designed and built very specifically in order to behave itself within those seemingly-minor constraints. 600 Ohms at 1 KHz was the target, and that was good enough for a very long time. But when frequencies increase into the MHz range with things like DSL, that characteristic impedance tends to drop to somewhere in the realm of 100 Ohms.
100 Ohms is, not coincidentally, around the same characteristic impedance that our Ethernet cables seek to provide at the frequencies we care about in that space. :)
Whatever that characteristic impedance is (at whatever frequencies are being used), when it matches what the termination impedance of the two endpoints are then we get an ideal transmission line. (That's always the target; an ideal transmission line is a glorious thing, indeed.)
But bad impedance match results in not just seemingly-obvious things like attenuation; it also introduces things like reflection -- signals bouncing back and forth, causing temporal distortions that obscure the desired signal. Bad matches also result in standing wave patterns where the length of the wire makes a difference, but shorter isn't better: The pattern of these standing waves within a wire are a function of the wavelength of the signal, not the overall length of the cable.
It's easy to make any of those things work within their designed uses and designated systems, where all of the effort to get this stuff right happens behind the scenes.
It's much harder to replace with bits of copper wire from the junk drawer and get reliably-good results.
For 1KHz in modern-ish POTS lines, that wavelength is around 40km. That's easy-enough to hand-wave away for lots of uses. The impedance matching can all be completely screwed and it really doesn't matter much for short runs.
But at 12.8GHz (the frequency maximum of USB 4) in a USB cable, the wavelength is only around 16mm. It's kind of a big deal to seek to have the little parts exactly-right in these seemingly-innocuous, hard-to-see ways. :)
And the impedance changes in-use, too. A kink in the wire produces an impedance aberration at that point that can be measured, and that can also be bad enough to produce practical issues that affect real-world performance.
Bad enough to fail the binary test you described today, even though the test was completely successful yesterday.
I'm a ham and took a number of EE/electromagnetism classes in college, so I totally understand what you're talking about with wire characteristics. I agree there's a ton of hidden complexity on these high bandwidth cables we can buy in the discount bin at electronics store.
> They plug the cable in to the equipment they already have, and it either works in the way they care about or it does not.
That's the thing though, I don't always have these things handy or ready to just plug something in quick and test. I'd like some kind of small device which can actually do some quick tests and see if it passes or fails at whatever power and bitrate more than just what the little identifier says it can do. Because, I agree, you can't trust the tag, there's a lot going on. And a cable that tested fine a year ago might be too messed up to work today.
In the end, it's also sometimes messy testing bandwidth given two random devices. Are they just being buggy with their handshake? Are we getting strange driver issues? Something else going on? A more dedicated tester tool can just be sure these two things definitely, without question should work just fine at whatever bandwidth they're trying to test with. And with a button press it does it and clearly gives the results. If it's not too expensive and you end up handling lots of questionable cables, sounds kind of nice!
> And the impedance changes in-use, too. A kink in the wire produces an impedance aberration at that point that can be measured, and that can also be bad enough to produce practical issues that affect real-world performance.
This is still true of a six figure oscilloscope testing the wire. If you're not manipulating the wire in realistic ways your super expensive tool isn't really going to answer that any more as the cheaper pass/fail. What might look just fine on the scope may look really bad when you bend it wrong or it gets a little internal crack or too much outside interference or something. You'll potentially be clued in to it being closer to being a messed up signal, but not necessarily.
Sure.
It's just like ethernet networks in this way: We can examine a cable and see if it works by plugging in some regular gear with it, and look at the success/error rate. Lots of people do this. It's an empirical way to see if a cable is good enough today, under present conditions, as a binary pass/fail state.
Or: We can examine a cable using specialized gear to characterize its performance, and then: We measure not just if the cable is good enough for today, but how close it is to the edge of acceptance it is. This allows a fantastic cable that is exceptionally excellent to be discerned from the ones that may be merely good-enough-under-present-conditions edge-cases.
From there, it may in fact be sane to suggest that the better-performing cable is likely to have better longevity as it inevitably degrades from human factors like...using the thing.
So basically, it's cheap for them to defraud the consumer, and prohibitively expensive for the consumer to adequately protect themselves from it. The absolute state.
For people who cannot, or do not want to spend fantastic amounts of money on cable testers, can you name any reliable cable brands that, generally or strictly, sell cables which match their marketing material?
I don't need absolute perfection, but I hate the idea of buying an expensive cable, and being lied to about how good the performance is. I don't mind paying more for quality, but its hard for me to really articulate any difference between two USB cables, except by maybe their length, and how "sturdy" one might feel compared to the other.
It wouldn't do a lot to solve the issue of various low quality cables I already own, but I wouldn't mind throwing money at a cable company that doesn't lie to its customers.
I go for anything that’s USB-IF certified. Personally the Amazon Basics USB4, 40Gbps, 240W are great price for value whenever they’re around $10:
https://camelcamelcamel.com/product/B0C93G2M83
At that price they’re my default “generic” cable. Unless I need a longer length or 80Gbps this is the main workhorse in my home. It’s nice just never worrying about discerning “charging” cable from “data” cable.
CableMatters is a very reputable brand if you need more variety in selection. Monoprice also seems to care about quality. CalDigit and Apple both have vested interest in providing quality cables. Strong brand is a good starting point, but even then I still try to stick with USB-IF certified offerings only.
Small question: did anybody succeed to pay via Apple Pay?
Give me the freakin bit error rate please.