Simple GTMetrix API implementation on Bash
Any recent version of these packages should work. They can be installed via repositories in almost all Linux distributions or with HomeBrew on macOS.
git clone https://github.com/komodin/gtmetrix-api-simple-bash.git
mv gtmetrix-api-simple-bash/gtmetrix.sh /usr/local/bin/gtmetrix-test
chmod +x /usr/local/bin/gtmetrix-test
gtmetrix-test [URL]