Citoid/Determining if a URL has a translator in Zotero
Zotero runs daily tests on their translators here:
You'll notice there are two links for each day- one for "server" and one for "chrome". Citoid uses the "server" translators.
You can see there the full list of translators, and whether they're supported or not, and how the tests are performing. If they're not supported, then they will not run. If status is "failure" they may also will probably not run (this means all tests failed). If there is a data mismatch, they'll still run but it's less likely to be good data. Partial failure means that it won't run on some urls but will run on others.
There are a few exceptions to this mapping; In production for wikimedia, we've enabled three translators. We've enabled Google books translator for "server" despite partial failure. The partial failure occurs on links to multiple books, a.k.a. search queries, so we simply ignore this and move on. We've also enabled Wiley Online which seems to consistently work well, and Science Direct which unfortunately fails frequently but will work on some links. You can enable disabled translators on your own server by manually editing the translator to have the 'v' flag. Our own translator repository is here; it is updated less frequently than the zotero repository, but contains our changes: https://github.com/wikimedia/mediawiki-services-zotero-translators
Also note that from the names of the translators is not always easy to tell whether some urls will work or not, since large publishers often have lots of journals under their wing. For example, Springer Science + Business Media translates a large number of journals, like the American Academy of Pediatrics. News sites often appear under their own translators.