Here are some example open source projects you may be interested in:

JSON API Formatter

The JSON API specification is a great way to implement APIs, with many classic API gotchas already resolved as part the precise response format. This set of classes allows these to be easily created and interrogated, meaning easy and reliable output/input processing in php. Works great with laravel, symfony and other frameworks.

Source Github
Installation via packagist/composer : composer require floor9design/json-api-formatter

Character Humaniser

A class that offers quick ways to make confusing/complex strings readable, for example passwords.

Passwords often give confusing/difficult outputs. For example: lower case l (lima) and upper case i (indigo) are similar in many fonts, and symbols such as tilde have names that are often unknown or difficult to remember.

Source Github
Installation via packagist/composer : composer require floor9design/character-humaniser

Event Feeds for Eventim - Wordpress plugin

Eventim are one of Europe’s premier ticketing and events companies in Europe. This plugin allows a WordPress site to easily import events from their events feed, including automatically on a schedule. It also offers templates and shortcodes for displaying this data out of the box.

The plugin was developed during a contract but is maintained as an open source project. It is hosted on the Wordpress plugins page.

Source Wordpress plugin page
Installation via Wordpress plugin installer