Small, powerful, full featured WYSIWYG editor
A Java class library of general usability
Swagger module for node.js
jsvim 4: xvi online
So many tools to help a writer work but not all of them are free!
A LaTeX editor with a built-in TeXSample service client
General-Purpose PDF Library for Java and .NET
Orwell Dev-Cpp with author authentication for homeworks
Localization tools built by localizers for localizers
Collaborators on a version-controlled .tex file can track changes.
MindRaider is a personal notebook and outliner.
A database to rapidly develop fiction