VFront
Open Source
VFront is a dynamic front-end for MySQL or PostgreSQL databases written in PHP and Javascript.
Xataface
Open Source
Xataface is an open source PHP framework for building PHP/MySQL applications.
Airtable
Freemium
Airtable is a spreadsheet-database hybrid i.e., the features of a database are applied to a spreadsheet.
Compare LibreOffice - Base with alternatives
Compare VFront and LibreOffice - Base and decide which is most suitable for you.
Compare Airtable and LibreOffice - Base and decide which is most suitable for you.
Compare Xataface and LibreOffice - Base and decide which is most suitable for you.