Wikipedia
TA-Lib
TA-Lib is an open-source software library of technical analysis indicators. The library provides about 125 functions like ADX, RSI, MACD, Stochastics, Bollinger Bands, candlestick pattern recognition. TA-Lib can be reused by trading software developers working with Excel, .NET, Java, Perl, Python, PHP, C or C++. It is distributed under a BSD License and can be freely bundled with open and closed source applications.
Used in EclipseTrader, JForex, NexTick.