Fontlist

Found at api.fontsource.org/fontlist.

Returns an object containing a list of fonts and the types associated with them.

{
...
"abeezee": "google",
"blackout-midnight": "league",
"material-icons": "icons",
"yakuhanjp": "other"
...
}

The only available types are google, league, icons and other. League is in reference to the League of Moveable Type.