TrinityCore uses (parts of or in whole) the following opensource software :

ACE (ADAPTIVE Communication Environment)
  http://www.cs.wustl.edu/~schmidt/ACE.html
  Version: 5.7.9

bzip2 (a freely available, patent free, high-quality data compressor)
  http://www.bzip.org/
  Version: 1.0.5

G3D (a commercial-grade C++ 3D engine available as Open Source (BSD License)
  http://g3d.sourceforge.net/
  Version: 6.09

jemalloc (a general-purpose scalable concurrent malloc-implementation)
  http://www.canonware.com/jemalloc/
  Version: 1.0.0
  
libMPQ (a library for reading MPQ files)
  https://libmpq.org/
  Version: 1.0.4

MersenneTwister (a very fast random number generator)
  http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
  Version: 0.4.2

SFMT (SIMD-oriented Fast Mersenne Twister)
  http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index.html
  Version: 1.3.3

MySQL (the world's most popular open source database software)
  http://www.mysql.com/about/
  Version: 6.0.2

OpenSSL (an opensource toolkit implementing SSL v2/v3 and TLS v1 protocols)
  http://www.openssl.org/
  Version: UNKNOWN

sockets (a GPL licensed C++ class library wrapping the berkeley sockets C API)
  http://www.alhem.net/Sockets/
  Version: UNKNOWN

utf8-cpp (UTF-8 with C++ in a Portable Way)
  http://utfcpp.sourceforge.net/
  Version: 2.3

vld (a free open-source memory leak detection system for Visual C++)
  http://sites.google.com/site/dmoulding/vld
  Version: 1.0

zlib (A Massively Spiffy Yet Delicately Unobtrusive Compression Library)
  http://www.zlib.net/
  Version: 1.2.5