Open source, self hosted, runs on multiple platforms:
Windows, Linux, Mac etc.
Has a ticketing system, roadmap, workflow, user management, Q&A discussions etc.
With the Bitnami stack you can also host your Trac server in the cloud.
Ranked in these QuestionsQuestion Ranking
Pro Open source
Written in Python.
Pro GIT and SVN support
Pro Database support
Supports PostgreSQL, MySQL and SQLite.
Pro Bitnami installer
Bitnami installer available.
Python can be slow sometimes.