Developer Spotlight: Chris Coyier, CodePen

Chris Coyier has been building on the web for over 15 years. Chris made his mark on the web development world with CSS-Tricks in 2007, one of the web's leading publications for frontend and full-stack developers.

In 2012, Chris co-founded CodePen, which is an online code editor that lives in the browser and allows developers to collaborate and share code examples written in HTML, CSS, and JavaScript.

Due to the nature of CodePen — namely, hosting code and an incredibly popular embedding feature, allowing developers to share their CodePen “pens” around the world — any sort of optimization can have a massive impact on CodePen’s business. Increasingly, CodePen relies on the ability to both execute code and store data on Cloudflare’s network as a first stop for those optimizations. As Chris puts it, CodePen uses Cloudflare Workers for "so many things":

"We pull content from an external CMS and use Workers to manipulate HTML before it arrives to the user's browser. For example, we fetch the original page, fetch the content, then stitch them together for a full response."

Workers allows you to work with responses directly using the native Request/Response classes and, with the addition of our streaming HTMLRewriter engine, you can modify, combine, and parse HTML without any loss in performance. Because Workers functions are deployed to Cloudflare’s network, CodePen has the ability to instantly deploy highly-intelligent middleware in-between their origin servers and their clients, without needing to spin up any additional infrastructure.

In a popular YouTube video on Chris Coyier’s YouTube channel, he sits down with a front-end engineer at CodePen, and covers how they use Cloudflare Workers to build crucial CodePen features. Here’s Chris:

“Cloudflare Workers are like serverless functions that always run at the edge, making them incredibly fast. Not only that, but the tooling around them is really nice. They can run at particular routes on your own website, removing any awkward CORS troubles, and helping you craft clean APIs. But they also have special superpowers, like access to KV storage (also at the edge), image manipulation and optimization, and HTML rewriting.”

CodePen also leverages Workers KV to store data. This allows them to avoid an immense amount of repetitive processing work by caching results and making them accessible on Cloudflare’s network, geographically near their users:

"We use Workers combined with the KV Store to run expensive jobs. For example, we check the KV Store to see if we need to do some processing work, or if that work has already been done. If we need to do the work, we do it and then update KV to know it's been done and where the result of that work is."

In a follow-up video on his YouTube channel, Chris dives into Workers KV and shows how you can build a simple serverless function — with storage — and deploy it to Cloudflare. With the addition of Workers KV, you can persist complex data structures side-by-side with your Workers function, without compromising on performance or scalability.

Chris and the CodePen team are invested in Workers and, most importantly, they enjoy developing with Cloudflare's developer tooling. "The DX around them is suspiciously nice. Coming from other cloud functions services, there seems to be a just-right amount of tooling to do the things we need to do."

CodePen is a great example of what’s possible when you integrate the Cloudflare Workers developer environment into your stack. Across all parts of the business, Workers, and tools like Workers KV and HTMLRewriter, allow CodePen to build highly-performant applications that look towards the future.

If you’d like to learn more about Cloudflare Workers, and deploy your own serverless functions to Cloudflare’s network, check out!