Either use your system’s packages, third-parity binaries or the source.
As for Windows, there is monit-windows-agent to try out.
grab the latest binaries
linux binaries
wget https://mmonit.com/monit/dist/binary/5.28.1/monit-5.28.1-linux-x64.tar.gz tar xzf monit-5.28.1-linux-x64.tar.gz
netbsd binaries
wget https://mmonit.com/monit/dist/binary/5.26.0/monit-5.26.0-netbsd-x64.tar.gz tar xzf monit-5.26.0-netbsd-x64.tar.gz
proceed
cp -i monit-5.28.1/bin/monit /usr/local/bin/ cp -i monit-5.28.1/conf/monitrc /etc
slackware
sbopkg -i monit cd /etc/
ubuntu/debian
apt install monit netcat nmap ksh # exim4 | postfix | mail-transport-agent sysvinit-core cd /etc/monit/
redhat/EPEL
yum install monit cd /etc/
netbsd
uname -r echo $PKG_PATH pkg_add -v monit rmdir /usr/pkg/etc/monit/monit.d/ cp /usr/pkg/share/examples/rc.d/monit /etc/rc.d/ echo monit=yes >> /etc/rc.conf ln -s /usr/pkg/etc/monit/monitrc ~/
https://mmonit.com/wiki/Monit/Installation
https://www.cyberciti.biz/faq/how-to-install-and-use-monit-on-ubuntudebian-linux-server/
Monit https://www.mmonit.com/monit/
Monit Source Code https://bitbucket.org/tildeslash/monit/