Since it was released (three years ago), GitHub's Atom Text Editor was a terrific open source programmer for developers along with other popular cross-platform applications like Sublime Text.
The new Atom text editor, Teletype, lets you collaborate with other developers in a project to write or edit the code with individual cursors and zero latency.
GitHub states that you'll be able to use your own key bindings, packages, and themes while working with Teletype, so you won't feel like you're using someone else's IDE. THE company it also states that your data is transferred over encrypted peer-to-peer connections, so you don't have to worry about anyone watching what you write in your code.
The app is still in beta, so it doesn't include some related features that could make collaboration easier, like a window conversations, so you can discuss changes and additions with your team in the same app.
Hopefully this feature will be added in the future.