yafu
Automated integer factorization
... SNFS, GNFS, SIQS, and ECM).
YAFU is primarily a command-line driven tool. You provide the number to factor and, via screen output and log files, YAFU will provide you the factors. There is also an interactive environment similar to MATLAB or PARI/GP, where you can type commands and store results. YAFU is very customizable, through the optional use of many many command line parameters and a very capable expression interpreter.