API retirement is the removal or shutdown of an application programming interface (API) that software, services, or users could previously access. A provider may retire an API when it is outdated, difficult to secure, or replaced by a newer interface. Applications that still rely on it can stop working when access ends.
In cyber security and operations, retirement matters because hidden dependencies can disrupt business workflows and complicate upgrades. Organizations should inventory API usage, identify application owners, and test replacements before a shutdown. If an older API must be re-enabled to restore service, treat that as a controlled, temporary exception: review its permissions and exposure, monitor its use, and plan a migration. Retirement alone does not indicate a security incident, but unmanaged legacy connections can increase operational and security risk.