> ## Documentation Index > Fetch the complete documentation index at: https://docs.traceten.com/llms.txt > Use this file to discover all available pages before exploring further. # Next.js > Add Traceten to a Next.js app using the App Router layout or Pages Router _document.tsx. ## What this lets you do Track AI-referred traffic across a Next.js application, including client-side navigations that don't trigger a full page reload. ## Before you start * Your Traceten site key, from **Sites → Install** in the [dashboard](https://app.traceten.com/dashboard). * A Next.js project (version 13 or later recommended). * Understand which router you're using: App Router (`app/`) or Pages Router (`pages/`). ## App Router (Next.js 13+) The App Router uses a root layout file (`app/layout.tsx`) that wraps every route. This is where the snippet goes. Open your root layout file at `app/layout.tsx` (or `app/layout.jsx`). Use Next.js's built-in `