Beautifier and language aware code comparison tool for many languages. It also minifies and a few other things.

The Web Markup Minifier (abbreviated WebMarkupMin) - a .NET library that contains a set of markup minifiers. The objective of this project is to improve the performance of web applications by reducing the size of HTML, XHTML and XML code.

​The C++ Web Framework (CWF) is a MVC web framework, Open Source, under MIT License, using C++ with Qt to be used in the development of web applications.

StandAlone Async cross-platform Minifier for the Web.

Jabber-транспорт для ВКонтакте (A jabber gateway to the VK social network)

EditiX XML Editor - A modern, open-source XML editor designed for developers and markup professionals.

An excellent Google Blogger theme (template）designed with Bootstrap and Blogger's XML syntax.

A HTML5 tutorials for beginners, An introduction to HTML5 building blocks, step-by-step guide to HTML5

StandAlone Async single-file cross-platform Prettifier Beautifier for the Web.

A Python library that provides an ergonomic, DOM-like model for XML encoded text documents.

Texmlbus (Tex to XML BUild System) supports the conversion process of documents written in LaTeX to pdf, html, xhtml or jats.

🌐 N2O.DEV: Open Source Enterprise Frameworks

DocBook XSL Stylesheets for SUSE branding

Apuntes y ejercicios que he hecho para aprender HTML, CSS y XML

Shlomi Fish’s Homepage Sources - www.shlomifish.org

⚒ Simple, lightweight, customizable (X)HTML and XML formatter / beautifier

static site checker (an opinionated HTML nitpicker)

XML / HTML / XHTML markup language generator for Hy

Linguistic Annotation and Visualization Tool for XHTML Documents

Library to convert and check EPUB 2 and 3