Nunjucks is a templating language, and the one that I use here on my website! This is a very simple tool which will compile Nunjucks into HTML, with a preview of what it should look like on Toyhouse.
The intent is for you to be able to fill out my layouts easier by taking advantage of Nunjuck's advanced features, but TH coders could also use this to write their own Nunjucks layouts if desired.
In which case, be aware that there is no autosave function so either write your code in a separate editor, or use an extension like form history control to make sure there's no data losses.
Please also note that Toyhouse has a limited whitelist, so if you're writing your own code or editing things beyond the variables, periodically check that everything is working on Toyhouse!