I've been thinking that FST could be well suited for building routers for web frameworks. I.e. matching request path `/foo/42` to a set of route patterns like `/foo/{id}` etc. As I understand FST should be near perfect for this use and could potentially allow very good performance. Especially if you can construct the FST at compile time. Somewhat surprisingly I haven't seen anyone doing anything in that direction though, and FST literature is bit difficult if you don't have formal NLP background