Vercel Marketplace integration

The Vercel Marketplace integration adds PostHog feature flags and experiments to your Vercel projects with billing handled through Vercel.

Choose this integration if you do not already have a PostHog account and you prefer to consolidate payment for PostHog inside your Vercel invoice.

Installing the integration

1. Go to the PostHog integration page on Vercel Marketplace
2. Click Install

This creates a PostHog organization and project, and adds environment variables to your Vercel project.

Environment variables

The integration adds these environment variables to your Vercel project:

• POSTHOG_PROJECT_API_KEY - Your project API key, used to initialize the PostHog SDK
• POSTHOG_HOST - The PostHog API host URL (either https://us.i.posthog.com or https://eu.i.posthog.com)

For client-side frameworks, you'll need to rename these variables in your Vercel project settings to expose them to the browser:

Server-side code can use the original names directly.

Installing the SDK

The fastest way to add PostHog to your application is using our installation wizard. Alternatively, follow your framework's guide:

• Next.js
• React
• Svelte
• All frameworks

By default, you'll also get session replay and event autocapture. If you prefer to use feature flags only, you can opt out:

posthog.init('<ph_project_api_key>', {
  api_host: 'https://us.i.posthog.com',
  autocapture: false,
  disable_session_recording: true
})

Using feature flags

To use feature flags in your application:

if (posthog.isFeatureEnabled('new-checkout')) {
    // Show new checkout
} else {
    // Show old checkout
}

import { useFeatureFlagEnabled } from '@posthog/react'

function App() {
  const showNewCheckout = useFeatureFlagEnabled('new-checkout')

  return showNewCheckout ? <NewCheckout /> : <OldCheckout />
}

For more examples, see our feature flag code guide.

Creating feature flags and experiments

Access the PostHog dashboard from your Vercel project's Integrations tab or directly at app.posthog.com.

Feature flags and experiments you create automatically sync with Vercel's flags dashboard.

For full documentation:

• Creating feature flags
• Running experiments

Billing

Billing goes through your Vercel account. View usage in Vercel under Integrations → PostHog.

See our pricing page for more details.

Limitations

• One organization per Vercel team - Cannot link multiple PostHog organizations
• Cloud only - No self-hosted support (US or EU regions available)
• Region cannot be changed - US or EU is selected during installation
• One-way team sync - Vercel team changes sync to PostHog, not vice versa

Further reading

• Feature flags documentation
• Experiments documentation
• PostHog on Vercel