Nuxt.js

PostHog makes it easy to get data about usage of your Nuxt.js app. Integrating PostHog into your app enables analytics about user behavior, custom events capture, session replays, feature flags, and more.

This guide covers Nuxt v4.x and v3.7+. For these versions, we recommend using @posthog/nuxt module for client-side capture.

The @posthog/nuxt module provides:

• Automatic client-side PostHog initialization
• Auto-imported composables for PostHog and feature flags
• Automatic exception capture for error tracking
• Source map configuration and upload for error tracking

For server-side event capture beyond error tracking, use the posthog-node SDK directly.

Using an older version? See our docs for Nuxt 3.0-3.6 or Nuxt 2.x.

Installation

Install the PostHog Nuxt module using your package manager:

npm install @posthog/nuxt

yarn add @posthog/nuxt

pnpm add @posthog/nuxt

bun add @posthog/nuxt

If your site sets a Content-Security-Policy, it needs to allow PostHog. This applies to the snippet and to package installs alike: the SDK lazy-loads extra bundles (session replay, surveys) from PostHog's CDN, and sends events to the ingestion host. PostHog serves from subdomains of posthog.com that change over time, so allow the wildcard:

PostHog AI

script-src 'self' https://*.posthog.com;
connect-src 'self' https://*.posthog.com;
worker-src 'self' blob: data:;

script-src covers the snippet and the lazy-loaded bundles, connect-src covers event ingestion and feature flags, and worker-src covers session replay. The toolbar needs a few more, or use a reverse proxy so everything is first-party. Failing to do so causes silent failures where capture and identify calls never send, so the integration looks complete while zero events arrive. Remember connect-src falls back to default-src, so default-src 'self' blocks event delivery even when the script itself is bundled.

Identifying users

Identifying users is required. Call posthog.identify('your-user-id') after login to link events to a known user. This is what connects frontend event captures, session replays, LLM traces, and error tracking to the same person — and lets backend events link back too.

Use a stable ID from your auth system when possible, not an email or display name. Send those as person properties instead. If your app has no other stable key, email works as a fallback if they are unique. Never a shared literal like "anonymous" or "user", which pools many people onto one person and corrupts their data. When no ID is available at all, skip the identify and retain the anonymous distinct ID that's automatically assigned.

Call posthog.reset() on logout, so the next person to use the browser doesn't inherit the last one's identity.

See our guide on identifying users for how to set this up.

If your app calls your own backend, tracing_headers adds X-POSTHOG-DISTINCT-ID and X-POSTHOG-SESSION-ID to matching fetch and XMLHttpRequest requests. This lets server-side SDKs link backend events, errors, and LLM traces back to frontend sessions and replays. Use hostnames only, without protocols or paths.

posthog.init('<ph_project_token>', {
  api_host: 'https://us.i.posthog.com',
  // Optional: send PostHog session/user context to your backend
  tracing_headers: ['api.example.com'],
})

This works in local development too, but match on the hostname alone: use 'localhost', not 'localhost:3000'. Ports are never part of a hostname, so a value with one in it never matches anything. localhost and 127.0.0.1 are also different hostnames — use whichever your app actually calls.

Tracing headers help you attribute events across front and backend consistently. When this isn't available, use your server-side stable IDs to deduce the matching distinctId, and pass it in when capturing the event.

Configuration

Store your PostHog keys in environment variables rather than hard-coding them. Add them to a .env file (and to your hosting provider). You can find these values in your project settings.

NUXT_PUBLIC_POSTHOG_KEY=<ph_project_token>
NUXT_PUBLIC_POSTHOG_HOST=https://us.i.posthog.com

Then reference them when you add the module to your nuxt.config.ts file:

export default defineNuxtConfig({
  modules: ['@posthog/nuxt'],
  posthogConfig: {
    publicKey: process.env.NUXT_PUBLIC_POSTHOG_KEY, // Find it in project settings https://app.posthog.com/settings/project
    host: process.env.NUXT_PUBLIC_POSTHOG_HOST, // Optional: defaults to https://us.i.posthog.com. Use https://eu.i.posthog.com for EU region
    clientConfig: {
      // Optional: PostHog client configuration options
    },
  },
})

Usage on the client side

The module provides the usePostHog() composable which is auto-imported and available in all your Vue components:

<script setup>
const posthog = usePostHog()

// Capture a custom event
posthog?.capture('button_clicked', { button_name: 'signup' })
</script>

Note: usePostHog() returns undefined on the server side during SSR, so use optional chaining ?. when calling methods.

Usage on the server side

The @posthog/nuxt module initializes a server-side client for error tracking only. For general event capture in Nitro routes, create your own posthog-node SDK client.

The @posthog/nuxt module makes your config available at runtimeConfig.public.posthog.

First, create a server utility to reuse the PostHog client across requests:

import { PostHog } from 'posthog-node'

let client: PostHog | null = null

export function useServerPostHog(): PostHog {
  if (!client) {
    const config = useRuntimeConfig()
    client = new PostHog(config.public.posthog.publicKey, {
      host: config.public.posthog.host,
    })
  }
  return client
}

Then use it in your server routes:

export default defineEventHandler((event) => {
  const posthog = useServerPostHog()

  posthog.capture({
    distinctId: 'user_123',
    event: 'server_event',
  })

  return { success: true }
})

Feature flags

The module provides auto-imported composables for feature flags. All composables return reactive refs that automatically update when flags are loaded or changed.

<script setup>
const isEnabled = useFeatureFlagEnabled('new-feature')
// returns true, false, or undefined
</script>

<template>
  <div v-if="isEnabled">Feature is enabled!</div>
</template>

<script setup>
const variant = useFeatureFlagVariantKey('experiment')
// returns the variant string, true/false, or undefined
</script>

<template>
  <div v-if="variant === 'control'">Control group</div>
  <div v-else-if="variant === 'test'">Test group</div>
</template>

<script setup>
const payload = useFeatureFlagPayload('config-flag')
// returns any JSON value or undefined
</script>

<template>
  <div v-if="payload">Config: {{ payload.value }}</div>
</template>

Error Tracking

For a detailed error tracking installation guide, including automatic exception capture and source map configuration, see the Nuxt error tracking installation docs.

Troubleshooting

TypeScript errors in posthog config: Remove the .nuxt directory and rebuild your project to regenerate config types.

PostHog not capturing events: Ensure you're using optional chaining (posthog?.capture()) since usePostHog() returns undefined during server-side rendering.

Next steps

For any technical questions for how to integrate specific PostHog features into Nuxt (such as analytics, feature flags, A/B testing, surveys, etc.), have a look at our JavaScript Web and Node SDK docs.

Alternatively, the following tutorials can help you get started:

• How to set up analytics in Nuxt
• How to set up feature flags in Nuxt
• How to set up A/B tests in Nuxt
• How to set up surveys in Nuxt