Synthi is an open web tool that instantly summarizes and synthesizes Hacker News threads and their linked articles, grouping every point of view by topic.

[Live demo here: https://prototypejam.github.io/synthesize/](https://prototypejam.github.io/synthesize/)

Why I Built This:

I love the deep discussions on HN, but I never have time to read a long article and a 400-comment thread. The tipping point for building this was when I nearly burned through my monthly API credits on another service just trying to synthesize a few threads! I needed my own tool.

How It Works:

1. Paste any HN thread URL into Synthi. 2. It instantly detects it and fetches the linked article. 3. Click "Full Analysis" for a unified, topic-based synthesis (with attribution to the article or the commenter). 4. Export the result, bookmark it, or listen to it (the output is text-to-speech friendly).

Key Features:

* Smart HN workflow: Auto-detects HN links for a one-click analysis. * Works with any URLs: Can also synthesize any two articles or pieces of text. * 100% client-side: All processing happens in your browser. No backend, no tracking. * Open source (MIT License): The code is yours to inspect, fork, and use.

The Code: [https://github.com/prototypejam/synthesize](https://github.com/prototypejam/synthesize)

A Note on the API Key:

Synthi is a "Bring Your Own Key" app. You'll need a Google Gemini API key, which is stored securely in your browser's local storage and never sent anywhere else.

For now, it's Gemini only, largely because the free tier on Google AI Studio is incredibly generous and a great way to get started. I'm considering adding support for other models like Claude or OpenAI via OpenRouter in the future.

I've been using this every day and I hope it's useful to some of you too. All feedback is welcome!