This looks pretty much open source: https://code.google.com/p/nativeclient/wiki/Source?tm=4 https://en.wikipedia.org/wiki/Google_Native_Client This Ubuntu bug (comment 2) says: "NaCl is its own toolchain, and upstream ships it by shipping a binary version of it, which is not OK IMHO" So building might require using binary blobs. https://bugs.launchpad.net/ubuntu/+source/chromium-browser/+bug/882942 Nevertheless, I think it would be great to ship this optionally via "non-oss". NaCl offers the great possibility to run Android apps on a desktop OS using ARChon. https://github.com/vladikoff/chromeos-apk/blob/master/archon.md