A deliberately small, local-first HTML/CSS/JavaScript playground built with SolidJS, Monaco Editor and a sandboxed iframe.
Open Plainpen · About the project
npm install
npm run dev- HTML, CSS and JavaScript intelligence through Monaco
- Sandboxed, debounced live preview and a manual Run action
- Console and runtime error capture
- Four workspace layouts plus single-editor focus
- Browser-local autosave
- Compressed, backend-free share links
- Light/dark themes and configurable editor font size
- Fixed and fluid preview viewport presets
- Search-friendly static project information and structured application metadata
There are no accounts, servers, feeds, build pipelines or framework abstractions.
Plainpen renders standard browser code directly into an isolated iframe using srcdoc. Pen state is saved locally and can be compressed into a versioned URL fragment for backend-free sharing. Monaco is loaded asynchronously after the lightweight SolidJS application shell so the interface can paint before the editor engine downloads.