checkip.cloud is an open source service that queries data files that cloud providers publish about their IP blocks and services. Data for the searched IP will be returned, if present.
Cloud providers publish different data. Not all fields will be the same between cloud providers. checkip.cloud currently queries AWS, Azure, GCP, M365, and Oracle Cloud.
API: An API endpoint is available at /api/ip/<ip>. The API endpoint returns a JSON object.
More information can be found in the GitHub repo.