Directus - Free and Open-Source Headless CMS
Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
Hyperquery - Data notebook built for speed, visibility, and collaboration
Sheety - Turn any Google sheet into an API instantly, for free. Power websites, apps, or whatever you like, all from a spreadsheet. Changes to your spreadsheet update your API in realtime. Neat
Graphy - Graphy is the tool for anyone who can teach & anything can be taught. From SMEs, Educators, Coaches, and Trainers to Professional associations & larger companies use Graphy.
Sheetsu - Turn Google Spreadsheet into API