PRODUCT

The document editor that thinks with you

Compose is a split-view editor where humans and AI work on the same document simultaneously. Write code, prose, or markup — see it render live.

Split-view editing

Write HTML, CSS, or Markdown on the left. Watch it render instantly on the right. The preview is sandboxed and updates as you type with zero configuration.

editor.html
1<div class="hero">
2 <h1>Hello World</h1>
3 <p>Built with Compose</p>
4</div>
Hello World
Built with Compose

AI that edits with you

Press Cmd+K anywhere in your document. Describe what you want — "add a dark gradient", "refactor this table", "translate to Spanish". AI modifies your document directly, not in a separate window.

<section>
<h2>Features</h2>
<ul>...
</section>
Cmd+KMake this a responsive 3-column grid with hover effectsApply

Multi-format workspace

Switch between HTML and Markdown with one click. Each document type gets proper syntax highlighting, language support, and preview rendering. PDFs and components coming soon.

HTMLMD
<style>
.card { border-radius: 8px }
</style>
HTMLMD
# Getting Started
**Bold** and *italic*
`inline code`

Embeddable anywhere

Compose runs as a standalone editor or embedded inside other apps via the Connector API. One editor component across your entire platform.

connector API
GET /connector/compose
{
"embed_url": "compose.casa/app",
"api_url": "compose.casa/api"
}
embedded in
Chorus
Tether
Newton
Siren

Under the hood

EDITOR
CodeMirror 6
FRAMEWORK
Next.js 15
AI
Claude API
PREVIEW
Sandboxed iframe
FORMATS
HTML, Markdown
DEPLOY
Standalone + Beam

Start composing

No account needed. Open the editor and build something.

Open Compose