[nocman]

Unless something has changed since last year, it is not truly "open source" if you're going by the Open Source Initiative's definition of "open source".

Evidently there are a number of restrictions placed on the source code that prevent this from being the case. There was a Reddit discussion about it at the time:

https://www.reddit.com/r/programming/comments/2vvs7i/cloud9_...

[benologist]

It is most definitely open source it is just not unconditional, maybe that will change now.

https://github.com/c9/core