gnupasswd
gnupasswd - gnu change user password
...). small, simpler for single admin / small linux bases.
For example: it can make plain /etc/passwd plain text password file (still) or use shadow - (login.c may do both).
A goal is to be old linux and no "depends problems" (ie, some required pam selinux audit kerb (+nis remove hacks) "to work as intended". These can contact remote computers during login if misconfigured and are complicated to know if secure.
gnupasswd has none of these (gnu has NIS, off by default)