> For the complete documentation index, see [llms.txt](https://docs.coherent.global/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coherent.global/spark-apis/execute-api.md).

# Execute API

Each Spark service can be called to perform calculations by calling the Execute API. The [API Tester](/navigation/api-tester.md) is the user interface to test the Execute API.

* The [Execute API (v3)](/spark-apis/execute-api/execute-api-v3.md) specification of the Execute API is the version that is currently being used in the [API Tester](/navigation/api-tester.md).
* The [Execute API (v4)](/spark-apis/execute-api/execute-api-v4.md) specification of the Execute API supports synchronous batching enabling multiple requests to be submitted at the same time. This API specification also forms the basis for using the [Batch APIs](/spark-apis/batch-apis.md) and [Introduction to XConnector](/xconnector/introduction-to-xconnector.md).