Guessing no, because of the Node.js plugin architecture ("need to call into C or C++?", "full access to the filesystem"). Really only the UI seems to be done in WebKit.

From a quick glance it looks like its architected the same as Light Table (Local node server that accesses the file system and a decoupled UI that connects over http and uses WebKit). If it works like that it could run in the browser. Not so easily from anywhere though

I believe that's the point -- it's web based.

Nope: "Atom is a desktop application based on web technologies." So it's using node.js internally, but it's not actually a webapp.

Brackets does the same, which is frustrating as platforms like FirefoxOS and ChromeOS emerge.

It'd be nice to see the backend be a drop-in replaceable API so it works just as well hosted in a browser/on a Chromebook/in a NodeJS process.

Fyi, the Brackets file IO layer is indeed drop-in replaceable: https://github.com/adobe/brackets/wiki/File-System-Implement.... The core team only maintains the standard desktop file IO backend, but others can be swapped in.

That's only one piece of making an editor run in-browser and cross-browser of course, but it's an important piece.

Also -- there are actually a couple ChromeOS ports of Brackets out there already (such as Tailor - https://chrome.google.com/webstore/detail/tailor/mfakmoghean...), but I'm nto sure if any of them are being actively maintained.

Try Codio: https://codio.com/

Tried it a month or so ago. Couldn't get Vim keybindings working well. Hands don't work without it anymore :/

Nitrous.io is pretty decent...