fastpen is described as 'Fastpen is an open source alternative to codepen that just stores the source code compressed, in the url' and is a Code Editor in the development category. There are more than 25 alternatives to fastpen, not only websites but also apps for a variety of platforms, including Mac, Windows, Self-Hosted and Linux apps. The best fastpen alternative is Replit, which is free. Other great sites and apps similar to fastpen are CodePen, jsFiddle, JSPad and JS Bin.
Replit is a collaborative cloud development environment offering in-browser IDE features like AI assistance, real-time collaboration, Git support, hosting, deployment, syntax highlighting, plugin extensibility, ad-free UI, dark mode, and live code sharing.
CodePen is a communal front-end development platform providing real-time HTML, CSS, and JavaScript previews. Users can build projects, test code, and enhance skills through challenges. Features include Presentation Mode for conferences and a vast active community for sharing and discovery.
JSFiddle is an online IDE service and online community for testing and showcasing user-created and collaborational HTML, CSS and JavaScript code snippets, known as 'fiddles'.
JSPad is a fast and lightweight online code editor for writing, testing, and previewing HTML, CSS, and JavaScript snippets instantly.
JS Bin is a collaborative open source JavaScript debugging tool. Enter Javascript in one pane and HTML in the other and see the result; share using a short URL. Choose popular JS libs from a menu, so you don't have to remember the URL.
kodeWeave is a realtime coding playground for HTML, CSS and Javascript. Similar to JSFiddle and JSBin, but kodeWeave was made to work offline but also as a prototyping application to build applications for desktop operating systems while on mobile devices.
CodeSandbox is an online editor with a focus on creating, sharing and importing new React projects
snippet.host is a minimal text and code snippet hosting. With memorable domain name, it is free, lightweight, with no ads or cookies. Features include syntax highlighting in multiple languages, easy-to-use API and Tor hidden service support.
TIO is a family of online interpreters for an evergrowing list of practical and recreational programming languages.
dabblet is an interactive playground for quickly testing snippets of CSS and HTML code. It uses -prefix-free, so that you won't have to add any prefixes in your CSS code. You can save your work in Github gists, embed it in other websites and share it with others.
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