OSOR - OSOR is the Open Source Observatory, a project to provide a framework for developing and executing autonomous observations.
GitHub - Originally founded as a project to simplify sharing code, GitHub has grown into an application used by over a million people to store over two million code repositories, making GitHub the largest code host in the world.
openDesktop.org - The website openDesktop.
GitLab - Create, review and deploy code together with GitLab open source git repo management software | GitLab
Freecode - Freecode (formerly known as Freshmeat) is one of the legit open source development platforms that will be the key for developers and programmers to have a streamlined process via having enhanced collaboration and coding leverages.
BitBucket - Bitbucket is a free code hosting site for Mercurial and Git. Manage your development with a hosted wiki, issue tracker and source code.