Developer

• Open Connector API - Coveo Enterprise Search 6.0  [+]
  Allows developers to write their own connectors—simple but efficient ones, as well as more complex ones—in order to crawl specific objects, repositories, etc. that are not supported by CES.
• Open Converter API - Coveo Enterprise Search 6.0  [+]
  Enables users to index documents from any format and fully customize the way documents are indexed.
• Push API - Coveo Enterprise Search 6.0  [+]
  Allows users to define a source for which documents are programmatically pushed in the index.
• Search Interface API Connector - Coveo Enterprise Search 5 
• Searching and Retrieving Results Through XMLSearch.aspx - Coveo Enterprise Search 6.0 
• Security Provider API - Coveo Enterprise Search 6.0  [+]
  Explains that the security model of CES can be extended by developing addition connectors that contain security logic.
• Web Service Reference  [+]
  Details the different Web service references.