SonicApi is a web service that extracts audio features such as pitch, tempo and key chord. The service also provides processing services such as correction of pitch, tempo and the addition of reverberation effects. It is the web service version of zplane high quality components used by many products/companies in the field such as ableton, Steinberg. Korg or Native Instruments.
I have written a library for accessing the online services from the .NET platform which uses the asynchronous version of the services. I’ve notified them about it and they decided to make it part of the official API, currently I am waiting for their review and instructions as they would like it to match the Objective C API they have developed internally.