TextAPI: C4 Maps of the Ecosystem for Digital Scholarly Editions

Heterogeneous collections, multiple formats, and evolving annotation practices pose significant challenges for Digital Humanities infrastructures. To move beyond isolated project silos, research environments must provide open and flexible access to cultural heritage. The TextAPI and its surrounding specifications SearchAPI, AnnotationAPI address this by defining stable, implementation-independent interfaces for accessing, searching, and presenting annotations for digital texts. The infrastructure is built on a loosely coupled, API-driven philosophy. By separating normative API contracts from specific back end implementations, we ensure long-term resilience and maintain the system as easy to adopt by others as possible. This approach lowers the barriers for community-built tools, allowing researchers, memory institutions, and the public to interact with textual data independently of the underlying repository technology. The poster visualizes this ecosystem using the C4 model to illustrate scope, responsibilities, and engagement boundaries. At the System Context level, TextAPI-based services are situated within the broader research environment, we highlight the interplay between end-users, client applications (TIDO), and external authority services. At the Container level, we present the deployable building blocks — including API endpoints, search back ends, and transformation modules. The accompanying live demonstration showcases the ecosystem in action. Instead of a single reference stack, we demonstrate how various clients can retrieve texts, run searches, and consume annotations across different back end technologies. A key example of this modularity is the integration with TextLPG, which provides complex graph-based text modeling, and TIDO, an open-source viewer that translates these API streams into an intuitive interface for the public. Together, the poster and demo highlight how a flexible, API-based architecture serves as a infrastructure for the public good. It demonstrates that standardization is not a constraint, but a catalyst for collaborative, sustainable, and participatory Digital Humanities research.