This paper presents ADISS, a generic and flexible search system designed to integrate heterogeneous authority file providers. Authority data is used to unambiguously identify entities such as persons, places, and institutions. As individual data providers typically do not offer both broad, universal coverage and domain-specific, in-depth data, many real-world application scenarios require combined access to multiple datasets. In the context of Digital Humanities, combining multiple authority data providers helps to improve the coverage and to resolve ambiguities more effectively during data curation. Instead of relying on separate endpoints to access multiple data sources, we address this need by aggregating the datasets and exposing them through integrated query and result models, thus simplifying access at the level of technical interfaces and schema integration. We present a highly configurable search API, which offers a diverse range of search and filtering options, to leverage the integrated data sources. We demonstrate its practical value through two active projects, that require semi-automatic retrieval, as well as user-centered search scenarios for different authority file providers. An evaluation based on manually curated data shows high retrieval accuracy, highlighting the system’s effectiveness. We further illustrate how ADISS’s generic and highly configurable design makes it adaptable and reusable for a wide range of use cases, and we outline directions for future improvements.