I'm making a new thread for a question asked in https://www.quantopian.com/posts/quantopian-as-r-and-d-environment which was not answered.
I would be much more enthusiastic about Quantopian if there was an offline mode to prototype in. That way we can use IPython which would allow for much quicker prototyping and also can plot/visualize quicker.
The offline code part should be easy since zipline is open source. I understand the issue is the market data access but would it be possible to release say a months worth of old data for a few tickers so we could setup an offline version?
We'd still run the official backtests online but could develop using our favorite tools offline and fine-tune things in the online IDE.