Emulators often get requests to add a scripting layer to the emulator, but there isn't really any good solution to this problem yet. Adding an embedded language to the emulator means that you are now locked to that language and implementation, limiting platform availability of the emulator, and restricting users to a single language.
EmuRPC makes it simple for emu devs to add a powerful and flexible RPC to their emulator with minimal effort. Just add a few callbacks, and EmuRPC will handle all of the protocol's details.
EmuRPC is under the MIT license, but links with libraries that are not MIT. These are wholly compatible with the MIT so it shouldn't be an issue.
Boost - Boost Software license 1.0