Sitespeed.io is a set of Open Source tools that makes it easy to monitor and measure the performance of your web site.
brew install httpstat
Lara is donating all of the proceeds from the book to various charities focused on getting girls and women into coding, including Girl Develop It, Women Who Code, and DonorsChoose projects like Growing "Girls with Gadgets"! and Girls Can Code, Too!. So if you enjoy the book, please consider buying it!