Best way to give a web UI to a C program?

I've built this appliance based on the BeagleBone Black (, and now I need to enhance it. I need to make it configurable, and I think the best way is to add a web server to it. The radio's code is written in C++ and runs as a daemon. The configuration is a JSON file it reads when it starts up. I need a webapp that can read and write this config file, then tickle the daemon into re-loading it.

Any recommendations? Thanks!

Nodejs . . .

You also can write a usual C application with GTK+ GUI and use Broadway back-end to run this application in a html5 browser window.