Publisheet - Publish your Excel sheets to the web as dynamic web applications with formula support.
Algo by AirDev - Turn a Google Sheet model into a web app in 5 minutes
CALCONIC_ - Build & add interactive calculators to your website! Choose from more than 50 premade calculators or build your own from scratch. No coding required. Free plan available. Zapier Integration. Publish Anywhere.
SpreadShare - Explore community-curated spreadsheets.
SpreadsheetConverter.com - Use online spreadsheets, smart forms and beautiful charts in your blog or website. Put your booking and order forms online. Show live charts. Change any cell and the online spreadsheet or live chart immediately updates itself.
Sheetsu - Turn Google Spreadsheet into API