With Suspicious Package, you can open up any PKG file in Quick Look (select the file and press the Space bar) to peek inside and get a better understanding of what you’re installing.

Apple eventually hid the option to install some types of untrusted software. Here's how to bring it back.

Suspicious Package is a free Quick Look plug-in which allows you to inspect package files (.pkg) on the Mac. Package files on the Mac are awesome, because they can install all of the various files ...