BuiltWith - Find out the technology behind websites
Publisheet - Publish your Excel sheets to the web as dynamic web applications with formula support.
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
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.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.
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.