CodePen
codepen.io
Write HTML, CSS and JavaScript in a tab and watch it render live
Free tierClassic
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stackblitz.com
Runs npm install and a Node dev server inside the browser itself.
A development environment where the package install and the dev server genuinely execute in your browser through WebContainers, so a Vite or React project boots in a couple of seconds and keeps working offline afterwards. Prefixing any GitHub repo URL opens it directly, which is the fastest way to look at someone's project without cloning it. Anything needing a native binary — image processing, database drivers, most of the Python ecosystem — will not install.
Questions
A genuinely usable free tier with paid plans for volume or team features. Only pure-JavaScript dependencies work; any package with a native binary fails to install.
No. StackBlitz does the work inside your browser, so the file never leaves your device — you can load the page, disconnect from the network, and it still works. That makes it a reasonable choice for material containing personal data.
Only pure-JavaScript dependencies work; any package with a native binary fails to install.
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