Visual Studio Online REST API Reference
The Visual Studio Online APIs are based on REST, OAuth, Json and service hooks - all standard web technologies broadly supported in the industry. The specific services and resources are described here.
Before you start, look at the information on getting started with these APIs, if you haven't already seen it.
Cloud load test
Projects and teams
Work item tracking
Overview | Attachments | Batch | Classification nodes | Fields | History | Queries | Recycle Bin | Reporting Work Item Links | Reporting Work Item Revisions | Revisions | Tags | Updates | WIQL | Work Items | Work Item Relation Types | Work Item Types | Work Item Type Categories