I'm mulling a hobby project with a REST back end and React front end.

Other than platform-specific adaptation (like Android app life cycle callbacks) I'd like the core to run on both Linux and Android, preferably out of the box. Naively, as a bare minimum, I'd think it's about running an HTTP server on the host, and hopefully with goodies like URL routing, JSON, and templating on top.

So far I've had no luck in nailing down one framework that'd work on both platforms. I heard of Spring Boot, but then there's a port for Android. There's Jetty, but then there's i-Jetty for Android, and so on. I can't claim my search had been thorough, either.

Any suggestions?