OpenPFGW

OpenPFGW, formerly called PrimeForm, is an open source primality testing program on the Intel platform that has found many of the large primes listed in the Prime Pages. It uses sieve methods, pseudorandom permutation (PRP) as well as methods for specific kinds of primes, as programmed by George Woltman for GIMPS. As of 2006, the largest prime it has found is $19\times 2^{2206266}+1$.

According to the Prime Pages, the official website is http://tech.groups.yahoo.com/group/primeform/a Yahoo! Group.