Polaris Office Web Sheet - Simple open Sheet files on browser without sign-up
API Connector by Mixed Analytics - Connect any API to Google Sheets.
Magic Spreadsheet - Human workforce and AI plugged into your Google Spreadsheets
SheetHub - SheetHub turns your spreadsheets (either Google Sheets or Excel Online) into a REST-ful JSON API.
Spreadsheet.com - Spreadsheets that come alive as applications
Hoss - Track and manage third-party APIs