Add Posthog Rn

Add PostHog to RN + Expo

Product analytics + feature flags + session replay + A/B tests in one tool. PostHog Cloud has a generous free tier.

Why PostHog over alternatives

PostHog wins for indie apps that want one tool for everything.

Install

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pnpm add posthog-react-native posthog-react-native-session-replay
npm exec --no -- expo install expo-application expo-device expo-localization expo-file-system

For session replay specifically:

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pnpm add @posthog/react-native-session-replay

Init (app/_layout.tsx)

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import { PostHogProvider } from 'posthog-react-native';

export default function RootLayout() {
  return (
    <PostHogProvider
      apiKey="phc_YOUR_KEY"
      options={{
        host: 'https://us.i.posthog.com',
        captureNativeAppLifecycleEvents: true,
        enableSessionReplay: true,
        sessionReplayConfig: {
          maskAllTextInputs: true,
          maskAllImages: false,
          maskAllSandboxedViews: true,
        },
      }}
      autocapture={true}  // tracks navigation, touches automatically
    >
      <Slot />
    </PostHogProvider>
  );
}

Track events

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import { usePostHog } from 'posthog-react-native';

function MyComponent() {
  const posthog = usePostHog();

  const onPurchase = () => {
    posthog.capture('subscription_purchased', {
      plan: 'yearly',
      price: 59.99,
      trial: true,
    });
  };
}

Identify users

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// On login
posthog.identify(user.id, {
  email: user.email,
  plan: user.plan,
  signupDate: user.createdAt,
});

// On logout
posthog.reset();

Feature flags

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const showNewPaywall = posthog.isFeatureEnabled('new-paywall-v2');
const variant = posthog.getFeatureFlag('paywall-headline-test'); // returns variant string

if (showNewPaywall) {
  return <NewPaywall />;
}

Set up flags in PostHog dashboard -> Feature Flags. Roll out by:

• % of users
• User properties (e.g., country = US)
• Cohorts (e.g., users who completed onboarding)

A/B tests

PostHog feature flags can be Multivariate:

• Control: 33%
• Variant A: 33%
• Variant B: 33%

Track conversion against the flag value. PostHog computes statistical significance automatically.

Session replay

Enabled in init. Watch real user sessions. Critical settings:

• maskAllTextInputs: true (always — privacy)
• maskAllSandboxedViews: true (system screens, e.g. payment sheets)
• Specific elements: wrap in <PHMaskView>

Privacy / disclosure

• Add PostHog to Privacy Manifest
• "We use PostHog for product analytics" in privacy policy
• PostHog is GDPR-compliant
• For EU users, use EU instance: https://eu.i.posthog.com

Common gotchas

• Autocapture creates a LOT of events (touches, screens) — enable thoughtfully
• Session replay is heavy on bandwidth; disable for users on cellular if metered
• Feature flags load async on first launch — cache last-known flag state for cold start
• posthog.reset() on logout clears the user identity but keeps anonymous events

Pair with

• add-sentry-rn for crashes (different concern)
• privacy-manifest-rn to disclose PostHog
• design-paywall for using flags to A/B test paywall variants