Open Source Software for Self-Hosted
StackEdit
StackEdit is an open-source, browser-based Markdown editor with a wide varity of features. It allows you to edit multi-Markdown documents in offline and online modes, lets you store documents in HTML and PDF formats, and collaborate with friends and co-workers though third-party cloud services such as Dropbox, GitHub and Google Drive. A bonus feature of StackEdit is the integration with blogging platforms like Blogger, Tumbler, and WordPress where your documents can be outputted as Markdown or HTML with Handlebars template engine
Gitea
Gitea is a free and open-source software package for hosting software development version control using Git The software is written in Go and is a community managed fork of Gogs, released under the MIT license. With Gitea you can host your very own software project collaboration platform that can handle bug tracking, wikis, code review and team communication.
Docusaurus
Docusaurus makes it easy to maintain open source documentation websites. With Docusaurus you can wriet docummentation and blog posts using Markdown and save time when doing so. Docusaurs automatically publish your files as static html files ready to serve on the web.
Gogs
Gogs is a painless self-hosted Git service that can be used to manage development projects. The lightweight footprint og Gogs allow you to host the software on the inexpensive Raspberry Pi.
Matomo
Matomo is the ethical alternative to Google Analytics that does not sacrifices user privacy. The web analytics platform provided by Matomo guarantees 100% data ownership and is provided as a free and open source self-hosted solution or a commercially managed service by Matomo itself.
Rome
Rome is a free and open-source JavaScript build tool that has strong conventions and aims to have minimal configuration. The toolset includes a linter, compiler and bundler for JavaScript, TypeScript, JSON, HTML, Markdown, and CSS. Rome has zero dependencies, and has largely been written from scratch by people from Facebook.
ProcessWire
With ProcessWire you can connect all your content seamlessly and making content management fast, easy and fun. ProcessWire is a free and open-source content management system and framework released under the Mozilla Public License 2.0. The CMS is built around an API wit similar naming connventions to that of jQuery, which makes it easier to use for JavaScript developers. It also provides a secure foundation, proven scalability and the performance needed to manage content online sucessfully.