Roel Nieskens released a tool that lets you upload a font file and see what’s inside, from how many characters it contains to the number of languages it supports. Here’s what you see once you upload a font, in this case Covik Sans Mono Black:
Why is this data useful? Well, I used this tool just the other day when I found a font file in a random Dropbox folder. What OpenType features does this font have? Are there any extra glyphs besides the Roman alphabet inside? Wakamai Fondue answered those questions for me in a jiffy.