I was running DetectX for a while when it stopped working after an upgrade to macOS. I removed it from my iMac. I am running macOS 15.4.1. Has DetectX been upgraded to run on macOS 15 or later? Sqwarq reference macOS 10 or later, but it also several.
The easiest way to find out, since it is completely free, is to just download it and see if it runs. If it refuses to run it won't hurt anything. In the latter case you can just trash it.
DetectX, being non-commercial, is a labor of love by its developer. He goes through periods where he gets busy with other things and DetectX will languish for a while. Then he will get a burst of enthusiasm (probably because folks write him and express their appreciation), and he will update DetectX. For a while he handed the product off to someone else, but apparently that didn't work ouit and he took it back.
To answer the question of whether DetectX is valuable...no anti-virus software for the Macintosh is terribly valuable. Everyone here should know by now that the Mac has very competent anti-virus software built-in, so you don't need a third party product at all, and that there is very little malware in the wild for the Mac in any case. Third party anti-virus products are mostly only useful to re-assure the paranoid that they aren't infected with anything.
The one thing that DetectX is unusually valuable for is getting rid of adware. For some reason Apple, and the commercial anti-virus software companies, don't care much about dealing with adware. (At least, not unless the adware does more than serve up ads.) But DetectX is excellent about dealing with adware. That said, I haven't heard from anyone who has been hit by adware for years now. I think that's because adware is very expensive to write, it's not a terribly effective way for the bad guys to make money, and it is really hard to disseminate adware effectively now. (Adware has never been self-disseminating on the Macintosh. For it to propagate, the bad guys must trick users into downloading something that seems to be something else. Adware used to commonly be disseminated in downloads from third party software downloading sites. For this reason, such sites are now out of favor.)
If you download DetectX please let us know if it does, or does not run for you, and what your hardware and software (i.e. OS) configuration is. For what it's worth, I often recommend Detect X, and I've yet to hear from a single person who has told me that it won't run on their Mac.
