Require.js is a very useful tool for building JavaScript applications. By dividing up the application into modules that get loaded in asynchronously, the overall performance of the application is greatly increased. Plus, running the require.js optimization tool concats and minifies the files which reduces the amount of HTTP requests and overall download size.

Zipline

Zipline is a Pythonic algorithmic trading library. The system is fundamentally event-driven and a close approximation of how live-trading systems operate. Currently, backtesting is well supported, but the intent is to develop the library for both paper and live trading, so that the same logic used for backtesting can be applied to the market.

Zipline is currently used in production as the backtesting engine powering Quantopian (https://www.quantopian.com) — a free, community-centered platform that allows development and real-time backtesting of trading algorithms in the web browser.