AI systems or platforms can provide interfaces (APIs = application programming interfaces) for third-party vendors and other AI-developing companies to augment AI systems with exter- nal services. APIs facilitate the transfer of data and communication between two programs. Developers can use them to search for, collect or share data, or to build and adapt functions into their own software products. A basic distinction is made between private APIs, partner APIs and public APIs. Private APIs can only be accessed by internal developers and workers within a single company. Restricted APIs, called partner APIs, can only be used by select companies under certain contractual requirements. Public APIs are freely available and can be used by any company without restrictions. Unlike open-source software, however, public APIs do not provide insight into the source code or allow for free customization. Public APIs are particularly beneficial to small and medium sized enterprises and NGOs, which often lack the resources and expertise to develop their own competitive AI software. Public APIs allow them to make processes more efficient and resource friendly and to flexibly integrate AI functions into their own software.