As long as you don't have to support IE11 or older browsers you could use <details> and <summary> natively.
Made with: HTML,CSS,JS
Slide from left accordion.
Made with: HTML,CSS
HTML list with an accordion-like structure. Mobile optimized and easily editable. CSS variables for the colors; built with Flexbox.
Animated accordion with HTML details element.
Made with: HTML,CSS (SCSS)
Accordion tabs without JS. This tabs have responsive design.
CSS vertical accordion for frequently asked questions.
Made with: HTML,CSS (Post CSS)
Pure CSS accordion with input edit.
Made with: HTML
Animated collapse/expend component.