Gitter

Gitter is an open-source instant messaging and chat room system for developers and users of GitLab and GitHub repositories. Gitter is provided as software-as-a-service, with a free option providing all basic features and the ability to create a single private chat room, and paid subscription options for individuals and organisations, which allows them to create arbitrary numbers of private chat rooms.
Individual chat rooms can be created for individual git repositories on GitHub. Chatroom privacy follows the privacy settings of the associated GitHub repository: thus, a chatroom for a private (i.e. members-only) GitHub repository is also private to those with access to the repository. A graphical badge linking to the chat room can then be placed in the git repository's README file, bringing it to the attention of all users and developers of the project. Users can chat in the chat rooms, or access private chat rooms for repositories they have access to, by logging into Gitter via GitHub
Gitter is similar to Slack. Like Slack, it automatically logs all messages in the cloud.
In late 2020, New Vector Limited acquired Gitter from GitLab, and announced Gitter's features would eventually be moved to New Vector's flagship product, Element, thereby replacing Gitter entirely.
Features.
Gitter supports:
Integrations with non-GitHub sites and applications.
Gitter integrates with Trello, Jenkins, Travis CI, Drone, Heroku, and Bitbucket, among others.
Apps.
Official Gitter apps for Windows, Mac, Linux, iOS and Android are available.
Advantages and disadvantages.
Like other chat technologies, Gitter allows users and developers to instant message (both users with developers, and developers with each other). Because of its integration with Github authentication and its web-based chat client, it is easy for developers who use GitHub to create or join a chat room without needing to install any extra software, or create another username/password pair to remember.
Maximalist GitHub permissions.
Gitter does not provide a regular password authentication. Instead, it asks for maximalist GitHub account permissions.
Pervasive logging.
The fact that messages posted to Gitter chat rooms are preserved indefinitely in chat room logs means that all users can see all messages in a chat room going back to when the chat room was created, which is useful for finding previous discussions and solutions to problems.
However, like logged IRC channels, Gitter has a tradeoff of greater convenience against lower privacy relative to unlogged IRC channels.
History.
Gitter was created by some developers who were initially trying to create a generic web-based chat product, but then wrote extra code to hook their chat application up to GitHub to meet their own needs, and realised that they could turn the combined product into a viable specialist product in its own right.
Gitter came out of beta in 2014. During the beta period, Gitter delivered 1.8 million chat messages.
On March 15, 2017, GitLab announced the acquisition of Gitter. Included in the announcement was the stated intent that Gitter would continue as a standalone project. Additionally, GitLab announced that the code would become open source under an MIT License no later than June 2017.
On September 30, 2020, New Vector Limited acquired Gitter from GitLab, and announced upcoming support for the Matrix protocol in Gitter. Gitter's features would eventually be moved to New Vector's flagship product, Element, thereby replacing Gitter entirely.
Implementation.
The Gitter web application is implemented entirely in JavaScript, with the back end being implemented on Node.js. The source code to the web application was formerly proprietary (it was open-sourced in June 2017), although Gitter had made numerous auxiliary projects available as open-source software, such as an IRC bridge for IRC users who prefer using IRC client applications (and their extra features) to converse in the Gitter chat rooms.