User onboarding, setup wizards, feature announcements, or, more generally, the modeling (and maybe implementation) of incremental, progressive user flows. The only caveat is that they tend to require the machine's state to be persisted so that the user doesn’t experience the same state(s) again.

Truthfully, using state machines at runtime for the use cases above is sometimes too heavy. That distinction is actually a big input to what I’ve been building at Dopt.

Our platform lets you build state machines that are initialized per user in your application via our SDKs—you design the machines in the platform, and we provide APIs to let you transition them based on user interaction/input. We’ve taken a bunch of inspiration from Xstate and statecharts. I actually wrote up a blog about how we took inspiration from the latter https://blog.dopt.com/state-machines-and-their-influence-on-...