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API Reference

Changing 'Orion' nomenclature

With the 2.8.1 release, we removed references to "Orion" and replaced them with more explicit, conventional nomenclature throughout the codebase. These changes clarify the function of various components, commands, variables, and more. See the Release Notes for details.

Prefect provides a number of programmatic workflow interfaces. Each API is documented in this section.

  • The Prefect Python API is used to build, test, and execute workflows against the Prefect orchestration engine. This is the primary user-facing API.
  • The Prefect Server API is used by the server to work with workflow metadata and enforce orchestration logic. This API is primarily used by Prefect developers.
  • The Prefect REST API is used for communicating data from clients to the Prefect server so that orchestration can be performed. This API is mainly consumed by clients like the Prefect Python Client or the server dashboard.

Prefect REST API interactive documentation

Prefect Cloud REST API documentation is available at

The Prefect REST API documentation for a local instance run with with prefect server start is available at http://localhost:4200/docs or the /docs endpoint of the PREFECT_API_URL you have configured to access the server.

The Prefect REST API documentation for locally run open-source Prefect servers is also available in the Prefect REST API Reference.

Prefect Cloud API rate limits

The Prefect Cloud API enforces rate limits, restricting the number of requests that a single client can make in a given time period. It ensures that, when you make an API call, you get a response. See Prefect Cloud API Rate Limits for details.