What are open-source tools companies use?

Hi there,

I'm looking for a list of of web-based open-source tools that companies usually use?

For example:

- Wordpress/Drupal/Joomla/Ghost

- Piwik/Matomo

- Woocommerce

- ...

Please help me compiling a list by writing down what comes to your mind or is used at your company.

EDIT: Formatting