Libelektra is a Library for Key/Values Pairs. There is an excellent API Description generated by Doxygen.
You might be interested in a short Tutorial to write your first elektrified program.
The API did not reach 1.0 status, so changes are possible. But you are welcome to implement your own libelektra using the API.
If your Program does not use C, you might be interested in Bindings.
If you want to use a different backend storage, go and see Backends.
See Roadmap how elektra is planned to evolve.
See Authors to see who is involved.