#1
Efficient, minimal collaborative code editor with real-time editing in the browser, OT-based syncing, WebSocket communication, and optional SQLite persistence.
4.1k stars215 forksMITlast commit Likely dormant
3 self-hosted CodePen alternatives
Web-based code editor and social development environment for building, previewing, and sharing front-end code (HTML, CSS, JavaScript). Offers live preview, hosted “Pens”, collaboration and asset hosting, plus community discovery of demos and prototypes.
Alternatives to CodePen
Open-source, browser-based code playground that runs entirely client-side; supports 90+ languages and embeddable demos, with Docker-based self-hosting.
1.5k stars265 forksMITlast commit Actively maintained
#3
Atheos is a self-hosted, web-based cloud IDE and code editor with a small footprint, featuring plugins, multi-user support, and built-in Git integration.
677 stars93 forkslast commit Actively maintained
What replacing CodePen actually involves
Every option on this page is open source and free to run on your own hardware, so you own the data and there is no subscription to cancel. 2 of 3 shipped a commit in the last six months. Licences in this list: MIT. In exchange you take on hosting, backups and updates yourself.
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