Analytics

Fathom Analytics

Configure Fathom Analytics

Copy the site ID from your Fathom embed code, where it is the data-site value. If your app changes routes without a full page load, also pass spa. Without it, the helper leaves Fathom's SPA route tracking off.

npm install @c15t/integrations@alpha

src/consent-scripts.ts

import { fathomAnalytics } from '@c15t/integrations/fathom-analytics';

export const scripts = [fathomAnalytics({ site: 'YOUR_SITE_ID', spa: 'auto' })];

Register the scripts

Complete your framework quickstart first. Keep its Inth endpoint, policy, styles and consent UI. Remove the vendor's original script, SDK initializer or tag-manager entry, so the vendor loads only through c15t.

The vendor pages put the helper in src/consent-scripts.ts. If your framework quickstart already has a scripts array, such as the one in c15t.config.ts in the Next.js guide, add the helper to that array instead of creating a second file. The scripts export is a configuration, not an initializer. Add it to the c15t provider you already have, at the registration point for your framework below. These are edits to that provider, not a second provider.

Add the configuration to scripts in c15t.config.ts, next to next.config.ts:

import { defineConsentConfig } from 'c15t/next';
import { scripts } from './src/consent-scripts';

export default defineConsentConfig({ scripts });

Keep the rest of your config, such as mode and routePrefix, in the same call. ConsentRoot reads the config in the browser, so the layout keeps passing only state. App Router, Pages Router and static export all read the same file. See Next.js scripts and embeds.

Options

Option	Default	Behavior
`site`	Required	Site ID, set as `data-site`. The helper trims it. Empty or whitespace-only values log an error and the script does not load.
`spa`	None	`'auto'`, `'history'` or `'hash'`, set as `data-spa`. When omitted, the script has no `data-spa` attribute and SPA route tracking stays off.
`auto`	None	Sets `data-auto` to `'true'` or `'false'` to control automatic page views. When omitted, Fathom's default applies.
`canonical`	None	Sets `data-canonical` to control canonical URL tracking. When omitted, Fathom's default applies.
`honorDnt`	None	Sets `data-honor-dnt` to control whether Fathom honors Do Not Track. When omitted, Fathom's default applies.
`scriptUrl`	`https://cdn.usefathom.com/script.js`	Loader URL override. A blank value falls back to the default.

Loading and revocation

fathomAnalytics uses the measurement category. Fathom sets no cookies, but the helper still waits for measurement permission. It loads script.js with defer. On revocation the helper removes the script element and calls no Fathom API. It does not call window.fathom.blockTrackingForMe.

Verify Fathom Analytics

After you allow measurement, script.js loads from cdn.usefathom.com and its script element carries your data-site and data-spa values. Change route in your app and check that it sends one page view, not two. If your code calls window.fathom?.trackEvent, check measurement permission before each call.

Test in a private window with an opt-in policy. Open DevTools Network, disable the cache and filter by the vendor's domain:

Load the page. No request goes to the vendor before you choose.
Click Reject, then reload. There is still no vendor request.
Open Privacy settings and allow the helper's category. The vendor script loads without a page reload.
Turn the category off again and save. c15t reloads the page, and the new page makes no vendor request.

c15t reloads on revocation because removing a script element does not stop code that already ran. The vendor's listeners, timers and queued events stay alive until the page unloads. If you set reloadOnConsentRevoked: false, stop the vendor yourself. Register a callback-only script whose onConsentChange calls the vendor's opt-out API, as shown in custom integrations, and check the permission before each of your own event calls. The reload does not delete cookies the vendor already set; see clear on revocation for your framework.

The helper sets vendor to its script ID, so once you declare that vendor a visitor can turn it off inside an allowed category. See vendor consent for your framework. The consent verification guide covers navigation, expiry and hosting checks.