You can use stylesheets and scripts hosted externally on your CodePen demo. Additionally, CodePen gives you access to a JavaScript console to debug your code if you are creating an element within the platform.
CodePen demos can be embedded in your website too. Embedded pens have previews of the code, which makes them ideal for technical writers while creating tutorials for front-end technologies.
CodePen allows you to fork the work of other developers and build upon it. Various views of your code are provided, but some are only available on the pro version, starting at $8/month billed annually.
While the strength of CodePen is creating and sharing pens, it introduced Projects in 2017, which allow you to create entire front-end projects on the site, making it a complete IDE.
JSFiddle is an early IDE that originated as a code playground, influencing many other competitors today. It allows you to create front-end elements and render them live in the browser.
