Installing the snippet

The snippet is a single script tag. Your dashboard's Setup instructions dialog shows it pre-filled with your tracking subdomain and client ID — and so does this page, once you've set your values from the top navigation:

<script async src="https://track.yourdomain.com/prism.js?id=cl_yourclient" data-cfasync="false"></script>

Place it before the closing </head> tag on every page you want tracked. It loads asynchronously (~3 KB) and does not block rendering.

Keep data-cfasync="false"

If the site is behind Cloudflare with Rocket Loader enabled, this attribute stops Rocket Loader from deferring the script and breaking early click-ID capture. It's harmless everywhere else — leave it in.

Running an e-commerce store?

Shopify doesn't use this snippet at all — its checkout runs in a sandbox this script can't execute in. Follow the Shopify install guide instead, which uses a custom pixel built for that sandbox.

WooCommerce uses this same snippet — install it as above — plus two order webhooks for reliable purchase totals. See the WooCommerce install guide.

Every other platform uses this same snippet, and gets the full e-commerce event journey — cart, checkout steps, purchases — for free if the site already has GA4/Google Tag Manager e-commerce tracking. See Detecting e-commerce with dataLayer for how that works.

Remove existing Meta pixel installs

If the site already runs a Meta pixel — hardcoded base code, the Meta WordPress plugin, or a Custom HTML tag in Tag Manager — remove it when Prism's Meta CAPI connection goes live. A legacy pixel running alongside Prism double-counts events and can carry hidden browser-side rules (Meta's Event Setup Tool) that fire events no code on the site explains. Removing it costs nothing: Prism generates the _fbp browser ID itself.

Full checklist of where pixels hide and how to verify removal: Meta CAPI → Remove existing pixel installs first.

What it does on load

1. Captures ad click IDs from the URL (fbclid, gclid, ttclid, and others) into 90-day first-party cookies.
2. Fetches a server-issued identity (adsidian_id, an HTTP-only cookie that lasts 1 year).
3. Fires an automatic PageView event.
4. Captures UTM parameters on every event.

Platform guides

WordPress

• With a theme that supports header scripts (Astra, GeneratePress, …): Appearance → Customize → Header scripts (naming varies), paste the tag.
• Any theme: install a header/footer script plugin (e.g. WPCode), add the tag to the header section, site-wide.
• WordPress.com (Business/Commerce): Tools → Marketing → Traffic or a header-script plugin as above.

Shopify

Don't use this snippet — see the dedicated Shopify install guide, which uses a custom pixel built for Shopify's checkout sandbox.

Webflow

Site settings → Custom code → Head code, paste, publish.

Google Tag Manager

Prefer a direct install when possible (GTM adds a loading layer that ad blockers target). If GTM is the only option: create a Custom HTML tag with the snippet, trigger on All Pages — Page View, and enable Support document.write off (not needed).

Plain HTML / other CMS

Paste into the shared header template so it renders on every page.

Single-page applications

The snippet fires PageView once per full page load. For client-side route changes in a SPA, fire a manual page view on navigation:

window.prism('track', 'PageView');

Next

• Verify your install
• Track custom events
• E-commerce events, if you're tracking a store