Salesforce APIs and supported formats

Synchronous

1. REST API - JSON, XML
2. SOAP API - XML
3. Chatter REST API - JSON, XML
4. Analytics REST API - JSON, XML
5. Apex REST API - JSON, XML, Custom
6. Apex SOAP  API - XML
7. Tooling API - JSON, XML, Custom

Asynchronous

1. Metadata API - XML
2. Streaming API - JSON
3. Bulk API - CSV, JSON, XML