[Fnoord]

> With a typeface, it's just this black box as to who is using some of the stuff, then you have no way of reaching back. You're completely reliant on whoever makes use of it tells you about it, which probably no one does, right?

I've seen multiple websites (What The Font being one of them) which analyses a picture with text. They then try to guess the font being used. If you could automate this process, you might be able to scrape content and figure out who's using your typeface. I guess that is mostly interesting for a commercial typeface looking for software piracy, though.

[mark-r]

What The Font does an amazing job sometimes, but it's not infallible. I'd say it misses more often than it hits.

Web crawling seems like a great idea, but probably not worth it just to get a list of customers. And it will never tell you who's using it in their app, or for signage.

[Fnoord]

What The Font was an example. I used multiple tools to find an obscure font. It was my first time trying to search for 2 fonts whilst I only had logo where the 2 fonts were used. One was relatively easy, the other one not. It cost me some time because like you say not every tool is as good as you'd expect it to be, but I did succeed.