Pretty much anyone who wants to play with applications for cryptography. Cryptocurrency stuff immediately comes to mind, but also things like identity management, code signing, communications, password/secret management, voting, and I'm sure there's more.
I think the better way to say it is that if you are just building apps, then you probably don't need this. But, as an example, I was just thinking about hacking together a workflow for writing/deploying signed Javascript, so a Javascript version of this library would have been perfect.
