Taskade - Make lists, organize your thoughts, and be inspired to get things done. Taskade is a collaborative space for your tasks.
BuiltWith - Find out the technology behind websites
Tatsu - Standup meetings for remote teams.
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
Any.DO - The #1 task management app used by over 11 million people globally, Any.do is your free mobile and online task manager for Android, iPhone, Web and more.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.