Sheet Best
Turn your google spreadsheets into JSON Database API
Everything without even logging in. This way you can use a SpreadSheet as the entire backend for your application just by providing a shareable link to it.
You can start using for free!
Its a great tool for small websites, startups, app landing pages and agencies.
Read the docs for more info about how to use the generated api
Check this out for an example of a app landing page created using SheetBest as a database.
Here are some screenshots: