"I found a tool called Yafu. It appears to be rather competent. It would require years of effort and advanced skills in math to write a better tool. For integers 320 bits and larger, Yafu requires GGNFS – a seriously very complicated piece of software that also hard to compile. Luckily there are nice windows binaries from Jeff Gilchrist. I also downloaded a binary version of Yafu for Windows. The examples below use Cygwin to have access to some Unix tools (bc, tr, openssl)."

http://techfindings.one/archives/1568 

yafu

Automated integer factorization 

  INSTALLATION --------------------------------------------------------------- No installation necessary, just put the binary in whatever location you like and run it. --------------------------------------------------------------- INSTALLATION WITH NFS SUPPORT --------------------------------------------------------------- To run the general or special number field sieve using yafu, you will need to provide ggnfs executable files and make the location of these files known to yafu at runtime. The easiest way to obtain the files is through Jeff Gilchrist's website: http://gilchrist.ca/jeff/factoring/index.html Download the .zip file for your OS and unzip it to a directory on your computer. The easiest way to let yafu know where these are is to modify your yafu.ini file (which should appear in the same directory as your yafu executable files) to contain a line specifying ggnfs_dir in the following way: ggnfs_dir= For instance, if your ggnfs executables were located adjacent to the yafu folder in the directory tree, in a folder called ggnfs-bin, then the line would be ggnfs_dir=..\ggnfs-bin\ --------------------------------------------------------------- PRE-COMPILED BINARIES --------------------------------------------------------------- Pre-compiled binaries have both GMP-ECM and selected msieve NFS routines built in (poly selection, linear algebra, and square root routines). For 32 bit windows, GMP-ECM 6.3 was linked against the MPIR-2.1.3 32 bit generic library. For 64 bit windows, GMP-ECM 6.3 was linked against the MPIR-2.1.3 64 bit core2 library. For 64 bit linux builds, GMP-ECM 6.3 was linked against GMP 5.0.1 x86_64 library. 32 bit linux builds currently are not provided All versions were linked against version 1.48 of msieve. --------------------------------------------------------------- BUILD INFORMATION --------------------------------------------------------------- Anyone is welcome to compile for your own system. If you can make a binary which beats the performance of one of the pre-compiled versions for a particular architecture, I'd love to hear about it!

https://sourceforge.net/projects/yafu/files/1.24/