# Elmo Chat

Creator · Lepton AI · 2024 – 2025

![Elmo Chat screenshot](https://www.yadongxie.com/projects/elmo-chat.webp)

Elmo read whatever was in front of you — an article, a YouTube video, a PDF, a Google Doc — and answered questions about it in a panel next to the page. No sign-up, no paste-the-text-into-a-chatbot step, and no cost to the reader.

I created it and built it at Lepton AI. The bet was that the summarize-this-page moment is worth owning end to end: it has to open instantly, work on the messy HTML of a real web page, stream an answer before you lose patience, and follow you into a video transcript or a PDF without changing tools.

![Elmo summarizing an essay in a side panel, with each point linked back to the paragraph it came from](https://www.yadongxie.com/projects/elmo-demo.webp)

*Every point in the summary indexes back into the page, so you can read the claim and its source side by side — the answer to not trusting a model's summary.* ([video](https://www.yadongxie.com/projects/elmo-demo.mp4))

The extension was featured on the Chrome Web Store, held a 4.6-out-of-5 rating, and passed 90,000 users on the number the site quoted — around 120,000 monthly actives at its peak.

I walked through how it was built, and what turned out to be hard about running an LLM against arbitrary pages, at Google I/O Extended Hangzhou in 2024.

Elmo has since been retired and elmo.chat is offline.

## Links

- [Slides — Build Chrome Extension with LLM](https://www.yadongxie.com/build-chrome-extension-with-llm.pdf)
- [Demo on X](https://x.com/yadong_xie/status/1808334735674094075)