How to Showcase Back-end Projects

I have recently just deployed my portfolio website online. However, since I don't have front-end projects that I can link my potential employers to codepen.io from my website, I'm left wondering how I can showcase my PHP projects. Are there any codepen.io equivalents out there but for back-end work? I've been recommended a couple but they don't quite work as suggested.

P.S. sorry if this is the wrong site to post, I suppose it's more business related than strictly coding.