Every symbol in the reference, counted by whether this engine runs it.
Counted from the reference at the moment you loaded this page. Nobody else publishes the last number; we publish it first, because the person about to rely on an answer deserves the availability question answered before the answer.
Available (45%) - the engine runs it, and every example on its page was executed.
Available, differs from the .wl reference (2%) - the engine runs it and is known to answer differently from the .wl reference; the page says how.
Implemented by the engine, not permitted on Qurak (1%) - the engine implements it and this deployment refuses it by policy - file, process and network access, mostly.
Not available (52%) - the engine does not implement it. The page exists so you find this out before you rely on it.
Every symbol, its status and its call forms, as one JSON document, cacheable and cross-origin readable. Cite it, diff it between rebuilds, or build your own comparison from it.
/api/docs/availability.json · Compared with the Wolfram Language