> ## Documentation Index > Fetch the complete documentation index at: https://docs.fitmyvehicle.com.au/llms.txt > Use this file to discover all available pages before exploring further. # How It Works > A small JavaScript snippet loads from our CDN. When a user clicks your quote button, it opens the FMV Accessory Builder in an iframe overlay on your site. ``` Your Website (your domain) → FMV Script (cdn.fitmyvehicle.com.au) → Builder iframe (cdn.fitmyvehicle.com.au/widget) → FMV API (api.fitmyvehicle.com.au) ``` ## The two parts The integration is a 2-part embed: 1. **fmv.js** (\~5 KB, no dependencies) — loaded directly on your page from `cdn.fitmyvehicle.com.au`. This is a lightweight UI shell that creates an overlay and iframe when the user clicks the trigger button. 2. **Widget iframe** — a full-page overlay iframe pointing to `cdn.fitmyvehicle.com.au/widget/`. All API calls, database connections, and data processing happen inside this iframe. Communication between the iframe and your page uses `postMessage` for close events and optional [analytics events](/configuration/analytics-events). No sensitive customer data crosses the boundary. ## Key details | Detail | Value | | ------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | Script size | \~5 KB (vanilla JS, no dependencies) | | Loading | Asynchronous with `defer` — does not block page rendering | | Lazy iframe | Created only when user clicks — zero impact on initial page load | | Time to interactive | \<100ms after script loads | | Widget iframe load | \~200–500ms on first open | | Event delegation | Uses event delegation on `document`, so trigger buttons work even if added to the DOM after the script loads (Shopify themes, WordPress page builders, SPAs, etc.) | | Compatibility | WordPress, Shopify, Wix, Squarespace, custom sites, and any platform that supports HTML | ## What the script does and doesn't touch The embed script (`fmv.js`) reads only its own elements: * Its own `