TruthMark

Verify What You Read, Instantly

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🚀 Inspiration

Every day, we’re flooded with bold claims online , from social media to news sites. But most people don't have the time or tools to verify what they read. I wanted to build something simple, fast, and accessible to help anyone question what they see online with just a double-click.

🔍 What it does

TruthMark is a Chrome extension that lets users fact-check any online claim instantly. By highlighting text and double-clicking, users trigger an AI-powered trust verification overlay showing a trust score, key context, and verified sources, all powered by the Perplexity SONAR API.

🛠️ How we built it

TruthMark consists of two parts:

  1. Chrome Extension - built with vanilla JavaScript, HTML, and CSS, with a content script that captures selected text and fetches verification via the SONAR API.
  2. Landing Page - built with Vite and TypeScript, optimized for fast load times and clean UI to present the project. The system uses minimal permissions and is privacy-first, with no data stored or tracked.

⚔️ Challenges we ran into

  • Designing a trust overlay that’s lightweight but still readable across different screen types.

🏆 Accomplishments that we're proud of

  • Built a fully working Chrome extension + demo landing page within the hackathon timeframe.
  • Created a truly useful, one-click tool that can help reduce misinformation.
  • Maintained a clean, privacy-first, open-source design, no cookies, no tracking.

📚 What we learned

  • How to build and deploy a production-ready Chrome extension.
  • How to integrate Perplexity’s SONAR API effectively for real-time trust evaluation.
  • Practical insights into user interaction on the web and the complexity of content injection.
  • The importance of minimalism and frictionless UX when fact-checking in real time.

🔮 What's next for TruthMark

  • Add a verification history panel so users can review claims they’ve checked.
  • Expand to Firefox and Edge.
  • Explore offline verification using cached context or LLM snippets.
  • Improve UI polish and animation for smoother user experience.

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