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
Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
SheetBest - Turn a Google SpreadSheet into a JSON Database API
Magic Spreadsheet - Human workforce and AI plugged into your Google Spreadsheets
Sheetsu - Turn Google Spreadsheet into API
Spreadsheet.com - Spreadsheets that come alive as applications