Tagxi

Tag your friends anywhere and everywhere on the web.

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Inspiration

While brainstorming ideas post-Bolt Hackathon, we realized link sharing while collaborating is still a hassle. Too many chats, too much context lost. Then it hit us — Twitter’s @ tagging changed conversations forever. Why not bring that to the entire web? Let people tag friends anywhere on any page. Simple, seamless, no friction.

What it does

  • Tag friends on any webpage at any text, image, or element using @username.
  • AI inside your browser auto-detects interesting lines or snippets worth tagging.
  • A companion site to view all your tags, memories, and friends' tags.
  • A lightweight social layer on your browsing.

How we built it

  • Chrome extension built using Plasmo + Tailwind + React
  • In-browser AI scanner using Hugging Face Xenova models
  • Companion web app for tag feed and profile
  • IndexedDB caching for offline tag memory
  • Clean, isolated DOM injection without messing up page styles

Challenges we ran into

  • Tagging on arbitrary pages is hard — because you don’t control the DOM structure. We had to carefully figure out how to inject tags, store their positions, and reliably find them again.
  • Making sure we didn’t mess up the existing page styling or functionality while injecting tags was tricky — we used isolated web components and shadow DOM where needed.
  • Keeping it privacy-friendly — tags are visible only to those tagged, and stored securely.
  • Building a clean, low-resistance UX. We wanted people to just use it naturally without onboarding friction.
  • Running AI models in-browser without killing the performance was a fun challenge too.

Accomplishments that we're proud of

  • It just works — select, @name, done.
  • Integrated AI tagging in-browser with zero server calls.
  • One login on the site auto-syncs your extension session.
  • Made it privacy-respecting, lightweight, and frictionless.
  • Learned isolated web components, IndexedDB, extension security, and running LLMs in-browser.

What we learned

  • How to properly build and package Chrome extensions
  • Injecting isolated UI components into arbitrary pages without breaking native page styles
  • Leveraging monorepos for cross-project dev flow
  • IndexedDB storage and syncing strategies
  • A deeper understanding of web security models like Same-Origin Policy and content script permissions
  • How to run transformer models inside the browser environment without melting it down

What's next for Tagxi

  • Build a personal archive hub where your tags live even if pages go down.
  • Turn tags into a personal memory graph — helping you track, rediscover, and make sense of your daily information flow.
  • Layer an LLM-powered insights system on top to connect your tagged content in smarter, contextual ways.
  • Make it more fun with leaderboard and streak system

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