xbar
Put anything in your macOS menu bar
xbar (the BitBar reboot) lets you put the output from any script/program in your macOS menu bar. xbar underwent a complete rewrite from the ground up in Go. You can browse all the plugins online, or write your own. To write a plugin, just write some form of executable script that outputs to the standard output. To write a plugin, you need to be able to produce some kind of executable (usually a script) that prints out lines of text. Variables are stored in JSON files alongside your plugin...