An application programming interface that provides programmatic access to a dataset, allowing software to query and retrieve data directly.
A data API lets developers access data without downloading entire files. Instead of downloading a 500 MB CSV, a developer sends a query to the API and receives only the records they need, in a structured format like JSON. APIs can also support filtering, sorting, and pagination.
Many open data portals offer data APIs alongside file downloads. APIs are particularly useful for data that changes frequently, because applications can always fetch the latest version rather than working from a stale downloaded file.
Example: The City of Toronto's open data portal provides a data API for its real-time parking availability dataset. A parking app queries the API every minute to get current availability at each lot, rather than downloading and parsing a new file each time.