An API Provider is you, if you wish to publish data from your API to on-chain contracts which are called requesters. You can do so by building an Airnode. An Airnode is a first-party oracle that will push off-chain API data to any on-chain requester. See the Developer section to learn more about how developers will use your Airnode.
See the Guides section in the API Provider docs to build the necessary files required to deploy an Airnode. The diagrams below illustrate the required components to successfully deploy an Airnode to AWS, GCP or a Docker Container.