PostHog

PostHog is an open-source product analytics platform that helps you understand user behavior, track events, and analyze product usage. Unlike traditional analytics tools, PostHog supports both cookieless and cookie-based tracking. This means you can sync c15t with PostHog and continue collecting analytics even when users haven't given consent—PostHog simply operates in cookieless mode until consent is granted.

PostHog SDK Implementation

This is the recommended approach if you're using the Posthog JS SDK, this is commonly used in React projects.

Adding the PostHog SDK to c15t

posthog.init("phc_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", {
  api_host: "https://eu.i.posthog.com",
  defaults: "2025-05-24",
  cookieless_mode: 'on_reject'
})

posthog.has_opted_out_capturing() // Avoids accidental tracking without consent till c15t has loaded

import { configureConsentManager } from 'c15t';
import { posthog } from 'posthog-js';

configureConsentManager({
  // ... 
  callbacks: {
    onConsentSet({ preferences }) {
      if (preferences.measurement) {
        posthog.opt_in_capturing();
      } else {
        posthog.opt_out_capturing();
      }
    }
  }
});

PostHog Script Implementation

If you want to load posthog via a script tag it's recommended to use this approach.

By default c15t will always load the script regardless of consent. This is because the script has built-in functionality to opt into and out of tracking based on consent.

posthog.init("phc_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", {
  api_host: "https://eu.i.posthog.com",
  defaults: "2025-05-24",
  // PostHog will not set any cookies until the user has given consent
  cookieless_mode: 'on_reject'
})

import { configureConsentManager } from 'c15t';
import { posthog } from '@c15t/scripts/posthog';

configureConsentManager({
  // ... 
  scripts: [
    posthog({ 
      id: 'phc_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx', 
      apiHost: 'https://eu.i.posthog.com',
      defaults: '2025-05-24', 
      options: { person_profiles: 'identified_only' }
    }),
   ],
});

Types

PosthogConsentOptions

Script