The paper discusses the question whether methods applied in work with prosopographical data can be integrated into an ”International
Proposography Interoperability Framework” (IPIF) comparable to the IIIF (International Image Interoperability Framework). It suggests
basing this upon a RESTful interface defined in a publicly available definition of an API. The API is based on the three-partite factoid
model, thus keeping the identification of the person, information on the person, and the source documenting this information separated,
aggregating it in a “factoid” with the metadata of its creation. The API definition follows the rules of OpenAPI which allows automatic
code generation. As a proof of concept, the API has been implemented in the context of the APIS project, containing the information
of the Austrian biographical lexicon, and with data from monasterium.net, the world wide largest database of medieval charters. It
introduces a wrapper for LOBID and wikidata and a standalone server created with code generation from the OpenAPI specification as
a second proof of concept implementation. In a third proof of concept it showcases the reuse of tools originally developed for APIS in
other services.