PostHog integration for Next.js App Router

This skill helps you add PostHog analytics to Next.js App Router applications.

Workflow

Follow these steps in order to complete the integration:

1. basic-integration-1.0-begin.md – PostHog Setup – Begin ← Start here
2. basic-integration-1.1-edit.md – PostHog Setup – Edit
3. basic-integration-1.2-revise.md – PostHog Setup – Revise
4. basic-integration-1.3-conclude.md – PostHog Setup – Conclusion

Reference files

• EXAMPLE.md – Next.js App Router example project code
• next-js.md – Next.js – docs
• identify-users.md – Identify users – docs
• basic-integration-1.0-begin.md – PostHog setup – begin
• basic-integration-1.1-edit.md – PostHog setup – edit
• basic-integration-1.2-revise.md – PostHog setup – revise
• basic-integration-1.3-conclude.md – PostHog setup – conclusion

The example project shows the target implementation pattern. Consult the documentation for API details.

Key principles

• Environment variables: Always use environment variables for PostHog keys. Never hardcode them.
• Minimal changes: Add PostHog code alongside existing integrations. Don’t replace or restructure existing code.
• Match the example: Your implementation should follow the example project’s patterns as closely as possible.

Framework guidelines

• Never use useEffect() for analytics capture – it’s brittle and causes errors
• Prefer event handlers or routing mechanisms to trigger analytics calls
• Add handlers where user actions occur rather than reacting to state changes
• Remember that source code is available in the node_modules directory

Identifying users

Call posthog.identify() on the client side during login and signup events. Use form contents to identify users on submit. If server-side code exists, pass the client-side session and distinct ID using X-POSTHOG-DISTINCT-ID and X-POSTHOG-SESSION-ID headers to maintain correlation.

Error tracking

Add PostHog error tracking to relevant files, particularly around critical user flows and API boundaries.