Those of you who know a thing or two about WordPress development have probably used custom functions in the past to customize your website. If you are new to coding, you may want to think twice about modifying your functions.php file. These two plugins make it easier to add your own functions and preserve them from future theme updates:
My Custom Functions: this plugin lets you add your own functions and code snippets safely. It keeps you from breaking your site by accident.
Functionality: this plugin works the same way as your theme’s functions.php file but protects your changes when you update your theme. Simply activate the plugin and add your custom code snippets.
If you know what you are doing, you won’t necessarily need these plugins. They can be a timesaver though.