Taj is a project mainly written in Clojure, it's free.
(iteration 0 "the mvp"):
quotes to persistent storage
simple options valuation based on quantlib
trading strategy: long under-priced assets
output trades to FIX
portfolio management (accounting of positions & orders)
simple web view of current portfolio
done:
quote stream integration (mbtrading)
quote parsing
(iteration 1 "speed & power")
watching multiple symbols
portfolio optimization, including transaction costs
second trading strategy: pairs trading
benchmarking: message turnaround time < 1 ms