Frink - A practical calculating tool, unit conversion utility, and programming language designed to make physical calculations simple.
Heytools - JavaScript tools, AJAX tools and some fully server side tools.
NimbleText - NimbleText is a text manipulation and code generation tool available online or as a free download.
WordCounter.net - Count words, sentences, paragraphs etc.
Event Viewer - Get help, support, and tutorials for Windows products—Windows 10, Windows 8.1, Windows 7, and Windows 10 Mobile.
TextBuddy for macOS - A Swiss Army knife for plain text.