HTML Viewer with Bidirectional Highlighting (Code ↔ Highlight Element)
Yet another online editor, but the two-way code-to-preview sync is actually useful.

GrapesJS already does embeddable visual editing with more features and community.
CMS developers, admin panel builders
GrapesJS · Builder.io · Craft.js
In my opinion, it is a good compromise between a lightweight rich-text editor and a heavy page builder and its easily embeddable into your website (especially into a CMS/admin panel)
Repo: https://github.com/neikiri/neiki-page-editor
I just really enjoy web components :D Would love to hear your feedback.
Yet another online editor, but the two-way code-to-preview sync is actually useful.
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Remotion alternative with pre-built Cursor and Claude Code skills for agent-driven video.
Yet another browser code playground, but shares snippets via URL hash instead of DB.