"Fossil is a simple, high-reliability, distributed software configuration management system with these advanced features:
Integrated Bug Tracking, Wiki, Forum, and Technotes - In addition to doing distributed version control like Git and Mercurial, Fossil also supports bug tracking, wiki, forum, and technotes.
Built-in Web Interface - Fossil has a built-in, themeable, extensible, and intuitive web interface with a rich variety of information pages (examples) promoting situational awareness.
This entire website is just a running instance of Fossil. The pages you see here are all wiki or embedded documentation or (in the case of the download page) unversioned files. When you clone Fossil from one of its self-hosting repositories, you get more than just source code - you get this entire website.
Self-Contained - Fossil is a single self-contained stand-alone executable. To install, simply download a precompiled binary for Linux, Mac, or Windows and put it on your $PATH. Easy-to-compile source code is also available.
Simple Networking - No custom protocols or TCP ports. Fossil uses ordinary HTTP (or HTTPS or SSH) for network communications, so it works fine from behind restrictive firewalls, including proxies. The protocol is bandwidth efficient to the point that Fossil can be used comfortably over dial-up or over the exceedingly slow Wifi on airliners.
Simple Server Setup - No server is required, but if you want to set one up, Fossil supports several different server configurations including CGI, SCGI, and direct HTTP. You can also easily set up your Fossil repository to automatically mirror content on GitHub.
Autosync - Fossil supports "autosync" mode which helps to keep projects moving forward by reducing the amount of needless forking and merging often associated with distributed projects.
Robust & Reliable - Fossil stores content using an enduring file format in an SQLite database so that transactions are atomic even if interrupted by a power loss or system crash. Automatic self-checks verify that all aspects of the repository are consistent prior to each commit.
Free and Open-Source - Uses the 2-clause BSD license."
I'm not even sure if this is an app or a feature but reading around the subject, it could be a good addition for devs this way inclined preferring it as an alternative to Git.