Offthread

Margin notes for Claude, ChatGPT, and Gemini.

Highlight any span in a reply, ask a short question beside it, and leave the main thread alone.

Get the extension View source

How it works

Three beats. Claude uses your logged-in session; ChatGPT and Gemini need a provider API key of your choice (one key covers both).

  1. Highlight

    Select a span in a Claude, ChatGPT, or Gemini message. Ask Offthread appears beside the host toolbar (or as a fixed chip).

  2. Ask

    A bubble opens in the margin with just that excerpt and your question.

  3. Stay in the gutter

    The answer streams into the bubble. Follow-ups stay there. The main chat never changes.

What stays out of the way

Built for side questions that would otherwise derail the thread.

  • Main thread untouched

    Each bubble is its own side conversation. Nothing is posted back into the parent chat.

  • Your keys, your device

    Claude rides the session you’re already signed into. ChatGPT and Gemini use an OpenAI or Gemini key you paste in Options — stored only on this device. No Offthread servers.

  • Soft persistence

    Margin threads save locally and reappear when you reload or return to a conversation.

Install

Get Offthread from the Chrome Web Store. Options opens on install — add an API key if you’ll use ChatGPT or Gemini, then highlight away.

Add to Chrome