What it is
Paste an address, a public GitHub repository, some source code or the output of git log, and it returns a percentage for how likely the thing is to have been machine-generated — with every piece of evidence that produced the number shown underneath it. It publishes the full catalogue of signals it reads and the weight each one carries, and it will issue a signed one-page PDF stating the reading and its caveats.
What it will not do
It says so itself, on its own front page: automated detection of this kind runs close to chance, and the number proves nothing. The evidence list is the useful part.
Why it is listed
It meets all four rules: free to use in full, usable without an account, honest about where the work happens, and clear about what it keeps. The rules are written down, and an app that stops meeting one of them is removed rather than quietly footnoted.
Something here out of date, or wrong? Say so on the issue tracker. The four answers above are the only thing this directory is asking to be believed about, so an entry that has drifted is a bug, not a detail.