Nuxt experiments installation

Install the package

Required

Install the PostHog JavaScript library using your package manager:

npm install posthog-js
yarn add posthog-js
pnpm add posthog-js

Nuxt version

This guide is for Nuxt v3.0 and above. For Nuxt v2.16 and below, see our Nuxt docs.

Add environment variables

Required

Add your PostHog API key and host to your nuxt.config.js file:

nuxt.config.js
export default defineNuxtConfig({
  runtimeConfig: {
    public: {
      posthogPublicKey: '<ph_project_api_key>',
      posthogHost: 'https://us.i.posthog.com',
      posthogDefaults: '2025-11-30'
    }
  }
})

Create a plugin

Required

Create a new plugin by creating a new file posthog.client.js in your plugins directory:

plugins/posthog.client.js
import { defineNuxtPlugin } from '#app'
import posthog from 'posthog-js'

export default defineNuxtPlugin(nuxtApp => {
  const runtimeConfig = useRuntimeConfig();
  const posthogClient = posthog.init(runtimeConfig.public.posthogPublicKey, {
    api_host: runtimeConfig.public.posthogHost,
    defaults: runtimeConfig.public.posthogDefaults,
    loaded: (posthog) => {
      if (import.meta.env.MODE === 'development') posthog.debug();
    }
  })

  return {
    provide: {
      posthog: () => posthogClient
    }
  }
})

Server-side setup

Optional

To capture events from server routes, install posthog-node and instantiate it directly. You can also use it to evaluate feature flags on the server:

npm install posthog-node
yarn add posthog-node
pnpm add posthog-node

server/api/example.js
import { PostHog } from 'posthog-node'

export default defineEventHandler(async (event) => {
    const runtimeConfig = useRuntimeConfig()

    const posthog = new PostHog(
        runtimeConfig.public.posthogPublicKey,
        { host: runtimeConfig.public.posthogHost }
    )

    posthog.capture({
        distinctId: 'distinct_id_of_the_user',
        event: 'event_name'
    })

    await posthog.shutdown()
})

Implement your experiment

Required

Experiments run on top of our feature flags. You can define which version of your code runs based on the return value of the feature flag.

For client-side experiments, use the JavaScript snippet. For server-side experiments, use the Node.js snippet:

if (posthog.getFeatureFlag('your-experiment-feature-flag') === 'test') {
    // Do something differently for this user
} else {
    // It's a good idea to let control variant always be the default behaviour,
    // so if something goes wrong with flag evaluation, you don't break your app.
}

// Test that it works
posthog.featureFlags.overrideFeatureFlags({ flags: {'your-experiment-feature-flag': 'test'} })

6
Run your experiment
Required
Once you've implemented the feature flag in your code, you'll enable it for a target audience by creating a new experiment in the PostHog dashboard.

Next steps

Recommended

Resource	Description
Creating an experiment	How to create an experiment in PostHog
Adding experiment code	How to implement experiments for all platforms
Statistical significance	Understanding when results are meaningful
Experiment insights	How to analyze your experiment data
More tutorials	Other real-world examples and use cases

Nuxt experiments installation

Install the package

Add environment variables

Create a plugin

Server-side setup

Implement your experiment

Run your experiment

Next steps

Community questions

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