cgit: https://git.zx2c4.com/cgit/about/
cgit seems more easy to use.
now I am browsing a file in
https://cgit.freebsd.org/src/tree/bin/cat/cat.c?h=stable%2F12
click the right upper switch button, I can quickly switch branches to view
the same file in different branches.
but git.postgres.org/gitweb checking the same file in different branches is
very hard.