Koha is a web-based, open source integrated library system designed for libraries of all sizes. It provides a range of features including circulations, catalogs, acquisitions, OPAC, administration, reporting and more in a customizable and flexible package.
Invenio-software.org is an open-source software framework designed for creating large-scale digital repositories for scientific, cultural, and bibliographic information. It is written in Python and offers modular and customizable features to support complex and diverse data management requirements.