Formerly known as Insert Headers and Footers by WPBeginner, is the most popular code snippets plugin for WordPress used by over 1 million websites. This simple insert headers and footers interface allows you to insert code like Google Analytics, custom CSS, Facebook Pixel, and more to your WordPress site’s header and footer as well other areas of your website. No need to edit your theme files! Aside from Header and Footer scripts, you can also use WPCode to insert custom PHP code snippets, JavaScript code snippets, CSS code snipets, HTML code snippets, and text snippets with full conditional logic

WPCode – Insert Headers and Footers + Custom Code Snippets – WordPress Code Manager