3.8 / 5

Highlight Synthesizer

Highlight text across the web, AI connects the dots

Useful

Privacy

The Problem

Highlights are scattered, disconnected fragments; synthesis requires manual effort

Current Solutions (Not Great)

Copy-paste to notes (tedious), highlighter extensions (collect but don't connect), manual synthesis

Who Needs This

Students, researchers, writers, anyone learning complex topics from multiple sources

You're reading about a complex topic across multiple articles—climate policy, a technical subject, a company's history. You highlight key passages as you go. Highlight Synthesizer collects these highlights and does something magical: it synthesizes them into a coherent understanding, notes contradictions between sources, identifies patterns you might have missed, and generates questions that arise from putting these pieces together. It's like having a research assistant who reads alongside you.

Honest Take

There are a ton of highlighter extensions (Liner, Weava, Hypothesis), but most just collect—the synthesis angle is unique and valuable. The challenge is that synthesis quality depends heavily on having enough context, and bad synthesis is worse than none. Great for students and researchers if you can make the synthesis genuinely insightful.

Monetization Ideas

Ways to turn this into revenue

Freemium

Free basic, $5-15/mo for pro

One-Time Purchase

$9-49 per license

Subscription

$5-29/month or $49-199/year

Features

Key features that make this app valuable

Highlight on any page with keyboard shortcut
Auto-capture source URL and context
Organize highlights by topic/project
AI-generated synthesis of related highlights
Contradiction detection between sources
Pattern identification across highlights
Generated questions from collected info
Export as structured notes or essay outline

Build Prompt

Use this prompt with an AI assistant to start building

Build a Chrome extension called 'Highlight Synthesizer' using WebInfer. Manifest V3 with activeTab, storage, sidePanel, contextMenus permissions. Content script: on Cmd/Ctrl+Shift+H, capture selection + surrounding paragraph + URL + timestamp. Context menu 'Add to Highlights'. Store in chrome.storage.local organized by user-created projects. Side panel: project selector, highlight list with source links, synthesis view. 'Synthesize' button sends project highlights to AI. Use generateObject to return { synthesis: string, themes: [{ theme: string, highlights: string[] }], contradictions: [{ point: string, source1: string, source2: string }], patterns: string[], questionsRaised: string[], gaps: string[] }. Display synthesis with linked citations back to highlights. Visual timeline of when highlights were collected. Export as markdown with citations. 'Generate essay outline' creates structure from highlights.

Score Breakdown

Pain