Several aren't working from the "coding ground"; and they did work yesterday.
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Interestingly I was going to suggest the idea of LibreCAD online
last week when I was thinking about
http://paperjs.org/I became aware of it back when
I was using adobe illustrator for geometric construction.
Scriptographer was a scripting plugin made by the same person,
which allowed me to write my own tools that AI lacked.
When adobe killed support for it, with cs6, I moved on.
After trying several programs I found LibreCAD thanks to
http://alternativeto.net/All that aside, my opinion about making an online version is: wait.
Let stuff grow a little longer.