Mashup APIs/Project Management

The Basecamp (Project collaboration service) API is implemented as vanilla XML over HTTP. You can also send requests in YAML format if you prefer, but all responses will be XML. Be sure to set the "Content-Type" header in your requests to "application/xml" (or "application/x-yaml" if you use YAML requests), which will identify the format of the data being sent. Also, you must set the "Accept" header to "application/xml", so that Basecamp will send you XML in reply, instead of HTML.