The Gliffy Java SDK by Gliffy allows API interaction to access drawings data, particularly useful to integrate diagrams and flowcharts into applications. Resources available include client, document, OAuth token credentials, and test account.
Online diagramming service Creately opened its Creately API to the public this month, and with some surprisingly innovative features. While providing obvious features to make its service available to outside developers, and several "above and beyond" features, such as easy embedding of diagrams, Creately has done something fairly unique: open up its own, web-based file format for other developers to use.
Chart APIs are useful and popular, and Google knows how to do them well, so they're continuously adding more features and options for customization to their Visualization API. The Google Code Blog recently highlighted a few of the newest features.
Google has announced the release a new production version of the Google Visualization API which includes several brand new features including timeline charts, donut charts, map data refresh for geoChart, customizable tick values and labels, and other chart improvements.