Every long-form article I read has the same failure mode: I hit a term I half-know, decide context is good enough, and move on. Twenty minutes later I've read 3,000 words and absorbed maybe 60% of them. The alternative — new tab, search, read, back-tab, find my place — costs about 90 seconds and kills whatever thread I was holding.
I built rabbitholes to close that gap without leaving the page.
Highlight any text and a shadow-DOM tooltip renders an explanation from Claude Haiku 4.5 directly next to your cursor. Shadow DOM specifically because an iframe overlay can't inherit the host page's fonts without a flash of unstyled content, and I didn't want the tooltip to look foreign on every site I use.
The part I actually use most: every word in the explanation is itself clickable. Drag across a phrase to select it and go deeper. The tooltip isn't a dead end — it's a starting point. Every answer surfaces two suggested rabbit-hole topics, the most interesting threads from wherever you've landed. There's a counter that tracks how many hops deep you've gone. If you make it to philosophy (and you will), the trail is shareable.
For cases where the model's training data isn't enough — current events, niche topics — a globe icon re-answers the query enriched with Brave Search results, with source chips inline.
Nothing phones home. Requests go directly from your browser to api.anthropic.com and api.search.brave.com. No intermediary server, zero telemetry. Your Anthropic API key lives in chrome.storage.sync, encrypted, and never leaves the browser. Manifest V3.
// The shadow root attachment that keeps the tooltip isolated
const host = document.createElement('div');
document.body.appendChild(host);
const shadow = host.attachShadow({ mode: 'closed' });
// All tooltip styles and DOM live inside shadow — zero bleed into host page
I've been using it for about three months on everything from academic papers to Hacker News threads. My read-through rate on dense material went up noticeably; I stop skipping past things I don't fully understand.
Top comments (0)