Heytools - JavaScript tools, AJAX tools and some fully server side tools.
SketchTool - Export pages & slices out of .sketch docs using CLI
WordCounter.net - Count words, sentences, paragraphs etc.
Select Similar Layers - Sketch plugin to select layers with the same attributes
TextBuddy for macOS - A Swiss Army knife for plain text.
Base UI Sketch Framework - Huge set of everything you need to design and prototype