Open source Version Control Systems

Centralized version control : Only one master copy of the software is used. 

Example : SVN, CVS

Distributed version control : There isn’t one centralized code base to pull the code from. Different branches hold different parts of the code.

Example : Git, Mercurial, Bazaar, Monotone, Fossil

CVS

• Very simple system for making sure files and revisions are kept up to date
• Earlier technology
• Still quite useful for backup and sharing files
• Tortoise CVS is a great client for CVS on Windows
• Many IDEs has plugins for CVS like : Xcode (Mac), eclipse, NetBeans and Emacs

SVN

• Widely used
• Most open-source projects use Subversion as a repository (SourceForge, Apache, Python, Ruby etc.)
• Many clients available : Tortoise SVN for Windows, Versions for mac, Xcode for Apple etc.

Git

• New rising version control systems
• Fast and efficient system
• Fast branching and merging operations 
• Not as easy to pick up as CVS or SVN, so it’s much harder to use for a beginner
• Initially developed by Linux kernel creator Linus Torvalds
• Every Git clone a complete repository and mirror of the original repository
• Clone contains the complete history of changes and full revision tracking facilities, and is not tied to a central server
• Many major open source projects uses or migrated to Git to power their repositories
  Example : Linux Kernel, WINE, Fedora, Rails, php etc.
• TortoiseGit is a GUI for using the Git SCM on Windows.
• Github powered the usage of git by providing beautiful front end.

Mercurial

• Extremely fast , high performance and scalable 
• used to handle large distributed projects
• Much simpler system than Git 
• Less functions to learn and similar to those in other version systems
• Also comes with a standalone web UI and extensive documentation
• TortoiseHg provides a GUI and explorer for Mercurial SCM

Bazaar

• offers a very friendly user experience
• supports many different types of workflows : solo / centralized / decentralized
• Easy to modify and setup
• allows users to commit their own branches of source code for particular application

LibreSource

• Web portal used to manage collaborative projects. 
• based on Java/J2EE and is more a set of visual collaborative tools to help facilitate projects and teams
• Collaboration hub for project development. 
• has built-in features such as Wiki pages, forums, trackers, Synchronizers, Subversion repositories, files, download areas, drop boxes, forms, instant messaging and more 
• provides tools which do not have a big learning curve

Monotone

• Monotone places higher value on integrity than performance. 
• Simply downloading the initial repository can take time due to the extensive validation and authentication required. 
• Fairly easy to learn if you’re familiar with other CVS systems
• It can import previous CVS projects
• Not quite as popular as other CVS

Fossil

• offers version control, bug tracker and technotes
• uses HTTP, HTTPS, or SSH
• Repository and its contents are stored in SQLite database
• Built in web interface in a stand-alone executable

SouceJammer

• 100% written in Java
• Source control and versioning system
• consists of 2 components :
• Server side : maintains files and version history, handles check-in/out etc.
• Client side : manages files at client-side and makes requests to server