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Integration Nextjs Pages Router

PostHogOfficialCreated by PostHog

  • Skill
  • Tool integration
  • Software development
  • MIT
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From the author

PostHog integration for Next.js Pages Router applications
— the description by PostHog

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a systematic approach to integrating PostHog into Next.js projects that utilize the Pages Router architecture. It covers client-side initialization, server-side tracking, user identification, and error tracking. The guide emphasizes best practices such as using environment variables, avoiding hardcoded keys, and maintaining clean event-handling logic by avoiding unnecessary useEffect hooks.

What it does

  • Provides a step-by-step workflow for PostHog setup
  • Demonstrates client-side initialization via instrumentation-client.ts
  • Shows how to implement server-side tracking for API routes
  • Guides user identification during authentication flows
  • Includes patterns for error tracking and feature flag usage
  • Offers a reference project structure for Pages Router applications

When to use it

  • When adding product analytics to a new or existing Next.js Pages Router application
  • When needing to track user behavior across both client and server boundaries
  • When implementing feature flags or session replay in a Next.js environment
  • When you need to ensure consistent event tracking patterns across your codebase

Advantages

  • Follows established patterns for Next.js Pages Router
  • Ensures secure handling of project tokens via environment variables
  • Promotes clean React code by discouraging misuse of useEffect
  • Supports both client-side and server-side event correlation

Usage examples

“How do I initialize PostHog in my Next.js Pages Router app?”
The skill directs you to create an instrumentation-client.ts file and configure it using your project token from environment variables.
“Where should I place event tracking code for user actions?”
The skill advises placing capture calls directly within event handlers rather than inside useEffect hooks.
“How do I track events on the server side in my API routes?”
The skill provides a pattern for using a server-side PostHog client to capture events in files located within the pages/api/ directory.
“How do I identify users after they log in?”
The skill shows how to use the posthog.identify() method within your authentication context or login logic.

Install

  1. Download the skill as a ZIP:

    https://autogineer.com/agent-skills/posthog/integration-nextjs-pages-router/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip integration-nextjs-pages-router.zip -d .agents/skills

Documentation by PostHog

PostHog integration for Next.js Pages Router

This skill helps you add PostHog analytics to Next.js Pages 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

  • references/EXAMPLE.md - Next.js Pages Router example project code

  • references/next-js.md - Next.js - docs

  • references/identify-users.md - Identify users - docs

  • references/basic-integration-1.0-begin.md - PostHog setup - begin

  • references/basic-integration-1.1-edit.md - PostHog setup - edit

  • references/basic-integration-1.2-revise.md - PostHog setup - revise

  • references/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

  • For Next.js 15.3+, initialize PostHog in instrumentation-client.ts for the simplest setup

  • For feature flags, use useFeatureFlagEnabled() or useFeatureFlagPayload() hooks - they handle loading states and external sync automatically

  • Add analytics capture in event handlers where user actions occur, NOT in useEffect reacting to state changes

  • Do NOT use useEffect for data transformation - calculate derived values during render instead

  • Do NOT use useEffect to respond to user events - put that logic in the event handler itself

  • Do NOT use useEffect to chain state updates - calculate all related updates together in the event handler

  • Do NOT use useEffect to notify parent components - call the parent callback alongside setState in the event handler

  • To reset component state when a prop changes, pass the prop as the component's key instead of using useEffect

  • useEffect is ONLY for synchronizing with external systems (non-React widgets, browser APIs, network subscriptions)

Identifying users

Identify users during login and signup events. Refer to the example code and documentation for the correct identify pattern for this framework. If both frontend and backend code exist, 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.

Files

references/basic-integration-1.0-begin.md

title: PostHog Setup - Begin description: Start the event tracking setup process by analyzing the project and creating an event tracking plan

We're making an event tracking plan for this project.

Before proceeding, find any existing posthog.capture() code. Make note of event name formatting.

From the project's file list, select between 10 and 15 files that might have interesting business value for event tracking, especially conversion and churn events. Also look for additional files related to login that could be used for identifying users, along with error handling. Read the files. If a file is already well-covered by PostHog events, replace it with another option. Do not spawn subagents.

Look for opportunities to track client-side events.

IMPORTANT: Server-side events are REQUIRED if the project includes any instrumentable server-side code. If the project has API routes (e.g., app/api/**/route.ts) or Server Actions, you MUST include server-side events for critical business operations like:

  • Payment/checkout completion

  • Webhook handlers

  • Authentication endpoints

Do not skip server-side events - they capture actions that cannot be tracked client-side.

Create a new file with a JSON array at the root of the project: .posthog-events.json. It should include one object for each event we want to add: event name, event description, and the file path we want to place the event in. If events already exist, don't duplicate them; supplement them.

Track actions only, not pageviews. These can be captured automatically. Exceptions can be made for "viewed"-type events that correspond to the top of a conversion funnel.

As you review files, make an internal note of opportunities to identify users and catch errors. We'll need them for the next step.

Status

Before beginning a phase of the setup, you will send a status message with the exact prefix '[STATUS]', as in:

[STATUS] Checking project structure.

Status to report in this phase:

  • Checking project structure

  • Verifying PostHog dependencies

  • Generating events based on project

Upon completion, continue with: basic-integration-1.1-edit.md

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Security

No issues found by our static scan· No issues found

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Attribution and licence

Created by
PostHog
Publisher
PostHog (Official)
Source
PostHog/skills · skills/posthog/integration/skills/nextjs-pages-router · commit a5d30e7
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
Synced
Also distributed in
PostHog/skills

AutoGineer is not affiliated with or endorsed by PostHog or PostHog.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download integration-nextjs-pages-router.zip