Question: I did not see the minifier among the tools in <https://code.trac.wordpress.org/browser/> . Is it in the repo somewhere? Or, what is it?

(Note this question has been asked previously on Stack Exchange but the author was really asking a different question, so it does not have an answer. See [What exact CSS minifier does WP core use?](https://wordpress.stackexchange.com/questions/218413/what-exact-css-minifier-does-wp-core-use) if you're really interested.)

Answer: 
According the the `Gruntfile.js` in core, the minifier is `grunt-contrib-cssmin` - <https://www.npmjs.com/package/grunt-contrib-cssmin>
Yeah, this minifier is present only in the development version of WordPress and it is not shipped with code that you can find in releases. They usually ship un-minified CSS and JS, with suffix `.min` for minified files. Also, based on a config option you can select which one to load between the two.

By development version of WordPress I mean the code resides in the SVN trunk (can be found [here](https://develop.svn.wordpress.org)). They also maintain a GIT mirror of the SVN repo, just for people who prefer using it.

One can play with their latest trunk by cloning the git repo locally:

```
git clone git://develop.git.wordpress.org/ wordpress-trunk
cd wordpress-trunk
# explore
#
# Gruntfile.js is the place where can one look at the 
# logic the core uses to build assets with

```