Mathesar is an open-source web interface that lets people view, edit and query PostgreSQL data in a spreadsheet-like view. It works directly with PostgreSQL schemas, tables and permissions, so the database's access rules apply. It targets both database administrators and business users, as an alternative to spreadsheet-style database tools such as Airtable. It is self-hosted on the organisation's own infrastructure, and a hosted version is also offered at mathesar.cloud.
Mathesar is maintained by the Mathesar Foundation, which the project describes as a 501(c)(3) nonprofit in the United States, and it is released under the GPL-3.0 licence. The project states that self-hosting keeps data on your own servers and that it is committed to remaining self-hostable. The website does not say where the hosted cloud service stores data, so organisations considering that option should check its terms. For a European organisation, running the open-source code on its own infrastructure limits dependence on a foreign provider.