Error Correcting Codes Page - Programs written in C/C++ and Matlab that implement encoding and decoding routines of popular error correcting codes. Collected by Robert Morelos-Zaragoza. - http://www.eccpage.com/
PAFF - Package for Algebraic Function Fields in one variable. Construction of geometric Goppa codes (also called algebraic geometric codes or AG-codes). Source code is available. - http://www-rocq.inria.fr/codes/Gaetan.Hache/PAFF.html
Error-Correcting Codes in MAPLE - Basic procedures for Cyclic, Hamming, Binary Reed-Muller, BCH and Golay codes. - http://web.usna.navy.mil/~wdj/codes.htm