Tinier Editor is a WYSIWYG text editor written in HTML5 and javascript based on code from Tiny Editor. My version is simpler, smaller and fixes a number of useability issues.
Back in 2011, while waiting for TinyMCE to download I spent a lot of time evaluating the multitude of WYSIWYG editors that were available before deciding which one to use on the Juggling Edge. Pretty much all of them were overcomplicated behemoths, packed with features that I didn't want with very poor cross browser support. After stripping away what I didn't want I found that they didn't do what I did want very well. I found the best of the bunch by far was Tiny Editor originally written by Michael Leigeber. However, this still had numerous issues which I have set about fixing. In doing so I have completely removed a number of features including the easy customisation options. My version of the editor is still completely customisable, you just need to be familiar with javascript to do so. I'm publishing this code primarily so other coders can see how I got over the problems they will inevitably be facing with their own editors!
View the source code, this can be minified to under 7KB.