CodePen Radio

Rachel and Chris jump on the show to talk about a bit of client-side technology we use: Apollo. We use it because we have a GraphQL API and Apollo helps us write queries and mutations that go through that API. It slots in quite nicely with our React front-end, providing hooks we use to do the data work we need to do when we need to do it. Plus we get typed data all the way through. Chris gets to learn that the Apollo Cache isn't some bonus feature that just helps makes things faster, but an inevitable and deeply integrated feature into how this whole thing works. Time Jumps

We're over 13 years old as a company now. We decide that we're not a startup anymore (we're a "small business" with big dreams) but we are still indie. We've seen trends come and go. We just do what we do, knowing the tradeoffs, and plan to keep getting better as long as we can. Links Timeline – Chris Coyier 115: Adam Argyle on Cracking the 2025 Web Dev Interview | Front-End Fire Time Jumps

Or just "Embeds" as we more frequently refer to them as. Stephen and Chris talk about the fairly meaty project which was re-writing our Embeds for a CodePen 2.0 world. No longer can we assume Pens are just one HTML, CSS, and JavaScript "file", so they needed a bit of a redesign, but doing as little as possible so that existing Embed Themes still work. This was plenty tricky as it was a re-write from Rails to Next.js, with everything needing to be Server-Side Rendered and as lightweight as possible (thank urql!). Time Jumps

Alex and Chris hop on the show to talk about a bit of technology that Alex calls "The 2nd best technological choice he's ever made." That technology is called Tree-sitter. It's a code parsing tool for building ASTs (Abstract Syntax Trees) out of code. GitHub uses it to power search and "go to" functionality. The creators now work on Zen, where a code parser is paramount. We use it to understand an entire Pen very quickly so we can understand how it all links together (among other things) and make a plan for how to process the Pen (a "build plan"). It's fast, accurate, forgiving, and extensible. Just a heck of a learning curve. Jump Links

Chris & Marie jump on the podcast to talk about just how drastically customer support has changed over the last few years. We still exclusively do customer support over email. Incoming email from real customers who need a hand with something where they type out that email in plain languages themselves are few and far between. Instead we get an onslaught of noise from users that don't exist about Pens and situations that don't exist. The influence of agentic AI is massive here, some of it with nefarious intent and some not. All of it needs work to mitigate. Time Jumps

Chris and Stephen talk about how we use a Cloudflare Worker & HTMLRewriter to inject a very special <script> tag into the previews of the Pens you work on. This script has a lot of important jobs so it's presence is crucial, and getting it in there reliably can is a bit of a challenge. Time Jumps

Chris and Stephen hop on the podcast to discuss the concept of a proxy. Possibly the most "gray hat" thing that CodePen does. We use a third-party analytics tool called Fullres. We could just put a link to the <script> necessary to make that work directly to fullres.com, but being an analytics tool, it's blocked by a ton of ad blocking browsers and browser extensions. We made the conscious choice to have that <script> point to a codepen.io URL instead (a proxy) so that we get (much) more accurate usage data on the app. Since there is nothing tracked that is an anonymity concern, and we do nothing with the data other than help inform ourselves on how to make a better app, we wear this gray hat. If you'd still like to block these requests, the path would be https://codepen.io/stats/fr/* Time Jumps

Robert and Chris jump on to talk about our little CDN project. Maybe that's not the right term, but we struggled with naming it. Truth be told, it's the /public/ folder in our monorepo, where the purpose is getting files to the world wide internet at URLs that anyone can access. Our favicon is a good example, where many of our sites need access to that, but we only want it once in our repo (but we have actually lots of use-cases.) There are several complications along the way. One is that we need to fingerprint these files so we can cache-bust them when needed. We also need to be able to import the URLs in other parts of the repo, so we need manifest files that contain those URLs in multiple formats. Plus many of the files have their own build process, they aren't just entirely static files. In the end, building our own thing was probably the right move. The files go to Cloudflare R2, which, I suppose, is the CDN part. Time Jumps

Marie and Chris jump on to discuss some of the trends of what people are building on CodePen here, approximately halfway through 2025. New CSS! Custom @functions (just landed) if() function clip-path & shape() corner-shape and the superellipse Scrolling stuff The attr() power up Hot Styles Liquid glass (Jhey's demo, Spark) Hard glitch (CRT-like effect with VFX-JS, Glitchy button hover effect with VFX-JS, ❍ Cinematic Glitch Slideshow) Holographics (CSS Holographic Masks) Grainy textures (Grainy distorted interactive 1 gradient blobs) Innovative blurs (wavy wobbly lava orb, Bubbles Background Animation) New color spaces (OKLCH Swatch Example, CSS Color Functions, CSS oklch Gradation) Hot Pens Petr Knoll’s Glass Button (From February, well ahead of liquid glass) Mike Bespalov’s Monospace ASCII art generator (known to be “vibe coded”) Adam Kuhn’s Severance Lumon Macrodata Refinement Steve Gardner’s “Who Needs Shaders” Time Jumps

Alex & Chris get into a fairly recent technological change at CodePen where we ditched our Elasticsearch implementation for just using our own Postgres database for search. Sometimes choices like this are more about team expertise, dev environment practicalities, and complexity tradeoffs. We found this change to be much better for us, which matters! For the most part search is better and faster. Postgres is not nearly as fancy and capable as Elasticsearch, but we werent taking advantage of what Elasticsearch had to offer anyway. For the power users out there: it's true that we've lost the ability to do in-code search for now. But it's temporary and will be coming back in time. Time Jumps

Stephen and Chris hop on to talk about how we're saving everyone from crashed browser tabs in CodePen's 2.0 editor. One simple: Executing JavaScript can cause a browser tab to entirely lock up, preventing you from doing anything, like potentially saving your work. It can even crash other same-domain tabs. But not on our watch! CodePen is now using a "heartbeat" technique to report up from the preview iframe to the parent page, and if we don't hear the heartbeat, we can rip out the iframe and stop the crash. But it was very tricky to get working and not too jumpy. Fortunately, we got it all working, because our previous technique of instrumenting your JavaScript wasn't going to scale well to the 2.0 editor. Time Jumps

Chris & Rachel hop on the show to talk about the expanded privacy (access) model in the 2.0 editor (in Private Beta as we speak). Private Pens have always been a big deal, but as private as they are, if someone has the URL, they have the URL, and it doesn't always feel very private. There are two new levels of privacy in the 2.0 editor: password protected and collaborators only. Passwords are an obvious choice we probably should have done long ago. With it, both the Pen in the editor itself, as well as the potentially deployed site are password protected. Our new permissions model is intertwined in this. Now you can invite others directly to be a fellow Editor or simply a Viewer to an otherwise private Pen. If you set the privacy level to "collaborators only", that's the most private a Pen can possibly be. Time Jumps

Pins are dead! Long live bookmarks! Pins was never a good name for the feature we have on CodePen where you can mark a Pen or Collection to more quickly jump back to it from anywhere on the site. The word is too similar to "Pen" that it's just awkward, not to mention it's not exactly and obvious metaphor. A bookmark is a much more clear term and icon, so we decided to switch to it. Switching the UI is kind of the easy part. It's kind of a cultural thing at CodePen, but when we make a change like this, we change it 100% through the entire code base, down to the database itself. In order to do that, we had to chunk it into stages so that those stages can roll out independently, but in order, to make it seamless. Now that it's done, we were able to extend the functionality of Bookmarks a bit, such that bookmarking a template is extra useful. One place to see that is on the new Create page. As an extra bit of history, the idea for Bookmarks came from Katie Kovalcin when we worked with Sparkbox for a redesign ages ago, then Klare Frake took the idea home. Time Jumps

Hi! We're back! Weird right? It's been over 2 years.  We took a break after episode 400, not because we ran out of things to talk about, but because we were so focused on our CodePen 2.0 work, it got old not being able to discuss it yet. We'll be talking plenty about that going forward. But CodePen has a ton of moving parts, so we'll be talking about all of it.  This week we'll be kicking off the podcast again talking about a huge and vital bit of CodePen infastructure: our email system. Outgoing email, that is. We get plenty of incoming email from y'all as well, but this is about the app itself sending email.  Timeline Links

Marie and I jump on the show to tell y'all we're taking a little break! It feels like years since we've been eluding to the fact that we're working on a new major upgrade to CodePen. Rather than keep dancing around it, we're going to minimize or remove working on anything that isn't working on that. We can't wait to come back for episode 401 and tell you all about it. Time Jumps Sponsor: Split This podcast is powered by Split. The Feature Management & Experimentation Platform that reimagines software delivery. By attaching insightful data to feature flags, Split frees you to quickly deploy, measure, and learn the impact of every feature you release. So you can safely deliver features up to 50 times faster and exhale. What a Release. Start raising feature flags (and lowering stress). Visit Split.io/CodePen for a free trial.

There was a small problem in our database. Some JSON data we kept in a column would sometimes have a string instead of an integer. Like {"tabSize": "5"} instead of {"tabSize": 5} of the like. Investigation on how that happened was just silly stuff like not calling parseInt on a value as it came off a <select> element in the DOM. This problem never surfaced because our Rails app just papered over it. But we're moving our code to Go in when you parse JSON in Go, the struct type that you parse it out into needs to match those types perfectly, or else it panics. We had found that our Go code was working around this in all sorts of ways that felt sloppy and inconsistent. One way to fix this? Fix any bad data going into the DB, then write a script to fix all the data in the DB. This is exactly the approach I took at first, and it would have absolutely fixed this problem. But Alex took a step back and looked at the problem a bit wider, and we ended up building some tools that helped us solve this problem, and solve future problems related to this. For one, we built a more permission JSON parser that would not panic on something as easy to fix as a string-as-int problem. This worked by way of some Go reflection that could tell what types the data was supposed to be and coerce them if possible. But what should the value fall back to if it's not savable? That was another tool we built to set the default values of Go structs to be potentially other values than what the defaults for their types are. And since this is all in the realm of data validation, we built another tool to validate the data in Go structs against constraints, so we can always keep the data they contain good. Once all these tools were in place, the new script to fix the data was much easier to write. Just call the safe JSON function to fix the data and put it back. And the result is a cleaned up code base and tools we can use for data safety for the long term. Time Jumps Sponsor: Split This podcast is powered by Split. The Feature Management & Experimentation Platform that reimagines software delivery. By attaching insightful data to feature flags, Split frees you to quickly deploy, measure, and learn the impact of every feature you release. So you can safely deliver features up to 50 times faster and exhale. What a Release. Start raising feature flags (and lowering stress). Visit Split.io/CodePen for a free trial.

Stephen and I hop on the podcast to chat about some of our recent tooling, local development, and DevOps work. A little while back, we cleaned up our entire monorepo's circular dependency problems using Madge and elbow grease. That kind of thing usually isn't the biggest of deals and the kind of thing a super mature bundler like webpack deals with, but other bundlers might choke on. Later, we learned that we had more dependency issues like inter-package circular dependencies (nothing like production deployments to keep you honest) and used more tooling (shout out npx depcheck) to clean more of it up. Workspaces in a monorepo can also paper over missing dependencies — blech. Another change was moving off using a .dev domain for local development, which oddly actually caused some strange and hard-to-diagnose DNS issues sometimes. We're on .test now, which should never be a public TLD. Time Jumps Sponsor: Notion Notion is an amazing collaborative tool that not only helps organize your company’s information but helps with project management as well. We know that all too well here at CodePen, as we use Notion for countless business tasks. Learn more and get started for free at notion.com. Take your first step toward an organized, happier team, today.

I was asked about the paradoxical nature of CodePen itself recently. CodePen needs to be safe and secure, yet we accept and gleefully execute user-authored code, which is like don't-do-that 101 in web security. Marie and I hop on the show to talk this through as an update from quite a long time ago. It's wonderfully-terribly complicated. Part of what complicates it is that there are many different kinds of worrisome code, from malicious, to distasteful, to spam, and they all need different treatment. This is a daily and never-ending war. Time Jumps Sponsor: Notion Notion is an amazing collaborative tool that not only helps organize your company’s information but helps with project management as well. We know that all too well here at CodePen, as we use Notion for countless business tasks. Learn more and get started for free at notion.com. Take your first step toward an organized, happier team, today.

Robert and I jump on the podcast to have a little chat about open source generally and what we do with open source at CodePen. CodePen itself is not open source, aside from the small bits we've made public and the open-source things we include within it. But all Public Pens on CodePen are open source, so we certainly handle a lot of it! Enough that I felt comfortable making our Mastodon presence on Fosstodon, which is an open-source-focused instance. Time Jumps Sponsor: Split This podcast is powered by Split. The Feature Management & Experimentation Platform that reimagines software delivery. By attaching insightful data to feature flags, Split frees you to quickly deploy, measure, and learn the impact of every feature you release. So you can safely deliver features up to 50 times faster and exhale. What a Release. Start raising feature flags (and lowering stress). Visit Split.io/CodePen for a free trial.

Marie and I hop on the show to discuss our recently released Most Hearted of 2022 Pens. We only did the calculations the day before, so this is more of a first reaction than a deep dive. Congrats to Hyperplexed for #1 and a massive year on CodePen. Last year, just one entry on the Top 100, and this year, nine. "Full layouts" like this appeared a number of times, including Aysenur Turk, last year's winner, at #13 with Liquid Transition Effect, and there were two NFT-themed landing pages (1, 2) in the Top 100. A lot of Pens attract attention when they have that "I could use this" feel to them, demonstrated by Ryan Mulligan's Logo Wall at #2! High five to Greensock for taking #3 with a re-creation of Brian Cross' lovely Pen. The tag "gsap" was used a ton in the Top 100. Jon Kantner took #4 and 10 other spots making this the most appearances on the Top 100 list ever, and also took a spot with a Pen made on December 13th! Aaron Iker and Yoav Kadosh both had 4 spots. Perhaps my favorite because of the deep CSS trickery involved was Scott Kellum's Apple inspired pride clock. Scott has the oldest account of anyone in the list, over 10 years old! Huge fan of Steve Gardener's joke, though as well. 11 of the Top 100 were created for CodePen Challenges. Time Jumps Sponsor: Notion Notion is an amazing collaborative tool that not only helps organize your company’s information but helps with project management as well. We know that all too well here at CodePen, as we use Notion for countless business tasks. Learn more and get started for free at notion.com. Take your first step toward an organized, happier team, today.