I'm looking for a way to find out, via web browser, perhaps by uploading or drag/drop of a font file in the most familiar extensions (.otf, .ttf, .woff, .eot) what OpenType features are present in a certain font file/type family.
It's somewhat similar to @PabloImpallari
font tester, with the difference of each OT Feature present in the font being highlighted and the others disabled in a list.
This would prove useful for the setting up of dynamic web type specimens, for example.
Does anyone know a tool that already does it? If not, what do you think would be necessary to build it (eg. reading a specific table from the font file, etc.?)