Peachnote is a search engine and analysis platform for music scores. Music Ngram Viewer and IMSLP search engine. When users enter melodies into the Music Ngram Viewer, it displays a graph showing how those melodies have occurred in a corpus of scores (e.g., "IMSLP") over the years.
The API offers a way of accessing the ngram data instead of downloading the whole data set. The API provides access to the latest and most complete music ngram data, which might not be available for download otherwise. It uses RESTful calls and responses are formatted in JSON and PNG.