Ask about one line — without losing your place.
Highlight any text in a Claude answer and a sleek, draggable side-chat opens right there, seeded with what you highlighted. Ask your side question, get a streamed answer, and your main conversation never moves.
SubChat starts a real, separate conversation on your own Claude account, using the session you're already logged into. Because the extension runs on claude.ai, its calls are same-origin and carry your cookies — exactly like the site's own frontend — so it can open a hidden conversation and stream the reply into the widget. No key to paste, no cost beyond your normal plan, and nothing leaves your browser except the request itself.
The published Chrome Web Store build targets Claude only. This repo also contains a ChatGPT adapter (
chatgpt.com) that works best-effort — OpenAI guards its endpoint with anti-automation, so Claude is the reliable path.
- Highlight → Ask → answer, right where you are
- Draggable, resizable, minimizes to a bar
- Streams in place with markdown + one-tap copy (replies and code blocks)
- Retry on errors, jump-to-latest, keyboard shortcuts (Enter to send, Esc to close)
- Multiple independent side-chats at once
- Clean light and dark themes
- A dashboard for preferences and live connection status
From the Chrome Web Store (recommended):
Install SubChat — side-chat for Claude from the Chrome Web Store.
From source (unpacked):
- Download or clone this repo.
- Open
chrome://extensions(Chrome, Edge, Brave, Arc…). - Turn on Developer mode (top-right).
- Click Load unpacked and select this folder.
- Open claude.ai (logged in), highlight text, click Ask.
The Claude-only build in dist/ is what ships to the Web Store; the
repo root is the full source (Claude + ChatGPT).
- Open claude.ai and highlight text in any reply.
- Click the Ask chip.
- Type your follow-up — the answer streams into the widget.
Open the dashboard from a widget's ⚙ button, the toolbar icon, or
chrome://extensions → SubChat → Details → Extension options.
No servers, no analytics, no tracking, no API keys. The only network calls are to the chat site you're already on, using the session you already have. See PRIVACY.md.
| Path | What |
|---|---|
manifest.json, src/, icons/ |
the extension |
src/content.js |
chip, widget UI, drag/resize/minimize, session adapters, streaming, markdown |
src/options.html / src/options.js |
the dashboard |
dist/ |
the Claude-only build that ships to the Web Store |
store-assets/ |
screenshots, promo tiles, listing copy, privacy policy |
Not affiliated with, endorsed by, or sponsored by Anthropic. "Claude" is a trademark of Anthropic, used here only to describe compatibility.
MIT © Soham Aggarwal