https://www.kernel.org and ftp://ftp.kernel.org contain all of the different versions of the Linux kernel source code. https://www.kernel.org/git/ contains a listing of all git trees in use by the different kernel developers.

https://gcc.gnu.org/ is the main site for everything related to the Gnu C Compiler.

https://www.gnu.org/software/binutils/ is the main site for all information about binutils .

https://www.gnu.org/software/make/ is the main site for all information about make .

https://www.kernel.org/pub/linux/utils/util-linux/ is the directory for where all versions of util-linux can be downloaded.

https://www.kernel.org/pub/linux/utils/kernel/module-init-tools/ is the directory for where all versions of module-init-tools can be downloaded.

https://e2fsprogs.sourceforge.net/ is the main project page for the e2fsprogs package.

https://jfs.sourceforge.net/ is the main project page for the jfsutils package.

https://www.namesys.com/download.html is the main project page for the reiserfsprogs package.

https://oss.sgi.com/projects/xfs/ is the main project page for the xfsprogs package.

https://sourceforge.net/projects/linuxquota/ is the main project page for the quota-tools package.

https://nfs.sf.net/ is the main project page for the nfs-utils package.

https://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html is the directory for where all versions of udev can be downloaded.

https://procps.sourceforge.net/ is the main project page for the procfs package.

https://cyberelk.net/tim/patchutils is the location for all of the patchutils releases.

https://git.or.cz/ is the main site for the git project.

https://www.selenic.com/ketchup/ is the main project page for the ketchup program.

https://savannah.nongnu.org/projects/quilt is the main project page for the quilt program.

https://distcc.samba.org/ is the main project page for the distcc program.

https://ccache.samba.org/ is the main project page for the ccache program.