Atom, GitHub's text editor, turned a corner for programmers this month with the May 6 announcement that it is now open source, available under the MIT License. Atom is still OS X-exclusive; prebuilt versions of Atom are currently only available for OS X (10.8 or later). GitHub, though, indicated that may not be the case for very long. Linux and Windows are in the wings. "Today," the team announced, "we're excited to announce that we are open-sourcing Atom under the MIT License." Development will continue supported by a dedicated team." In the next few months, we'll be focusing on improving performance, releasing on Linux and Windows, and stabilizing APIs. We think being open source will help us get there faster, and more importantly, source access will give you the transparency and control you've told us you expect from your tools."
Since the time they launched the Atom beta, every Atom package—and much of Atom's functionality is provided by packages—have been open source, but the significance of this month's announcement is that the rest of Atom has been open sourced. This includes the core application, package manager, and Atom's Chromium-based desktop application framework, Atom Shell. (Chromium is the open source project behind Google's Chrome.)
One important distinction about Atom is its ability to make use of web technologies without being restricted by web technologies, The Atom site explains: Atom is a desktop application based on web technologies. Like other desktop apps, it has its own icon in the dock, native menus and dialogs, and full access to the file system. As developer Nathan Sobo said in February, in the Atom blog: "So when we set out to write a text editor that we ourselves would want to extend, web technology was the obvious choice. But first, we had to free it from its chains."
He noted that while web browsers are great for browsing web pages, "writing code is a specialized activity that warrants dedicated tools. More importantly, the browser severely restricts access to the local system for security reasons, and for us, a text editor that couldn't write files or run local subprocesses was a non-starter." In turn, they did not build Atom as a traditional web application but instead as a variant of Chromium designed as a text editor rather than web browser.
As for its going open source, Sobo said in the May 6 announcement, "As Emacs and Vim have demonstrated over the past three decades, if you want to build a thriving, long-lasting community around a text editor, it has to be open source."