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RunJS vs CodePen: catalog facts
RunJS	CodePen
Free Free to download; no signup required according to the site.	Freemium Free to use, with paid plans for additional features.
Windows, macOS, Linux	Web
Live evaluation as you type, no project setup Node.js and browser environments in one app	Live preview of HTML, CSS and JavaScript as you type Nothing to install
JavaScript and TypeScript-style scratch work only, not a full editor Source code is not published	Needs an internet connection Suited to small demos rather than full projects
Downloadable app	Web application
Closed source	Closed source
License not stated	License not stated
No account needed	Not stated if an account is needed
Not stated if it works offline	Needs internet
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked September 24, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.