joodalint, a linter for catching errors in prose formatting and build output in Markdown-based sites.
tldraft is my take on a collaborative document editor, built to work completely offline too.
Pager is how I build single-page sites out of HTML and Markdown files, like the WEBCRAFT site.
Hugoloop is my opinionated take on how to structure a Hugo site, it provides an easily-understood, usable starting point for beginners and veterans alike.
A sync engine called SSSync for building offline-first apps with stateless backends, being designed in fits and starts.