Please let me share μcuREST - a C++11 library for implementing REST services on constrained platforms, such as bare metal applications on low-end MCUs. The library allows easy implementation of RESTful applications. Within your application you define a resource map, pointing to your variables/functions and μcuREST makes it accessible via HTTP. Please visit this link for a conceptual description. Sources are available on GitHub.
The library comes with an example of Web Admin Panel for NodeMCU v3 board. A prebuilt binaries of this example are available for downloading.
Here are the screenshots of this example: