How to identify and track users on PostHog

First, ensure PostHog is properly installed in your application. For web applications, add the PostHog snippet to your HTML or install via npm:

npm install posthog-js

Initialize PostHog with your project API key:

import posthog from 'posthog-js'
posthog.init('your-api-key', { api_host: 'https://app.posthog.com' })

Use the identify() method to associate a unique identifier with the current user. Call this method when a user logs in or when you have identifying information:

posthog.identify('user123', {
  email: 'user@example.com',
  name: 'John Doe',
  plan: 'premium'
})

The first parameter is the unique user ID, and the second parameter contains user properties.

Add or update user properties using setPersonProperties() to enrich user profiles with demographic, behavioral, or account information:

posthog.setPersonProperties({
  company: 'Acme Corp',
  role: 'admin',
  signup_date: '2026-01-15',
  trial_expires: '2026-02-15'
})

These properties will be associated with the identified user and available for analysis.

Capture specific user actions using the capture() method to track behaviors and interactions:

posthog.capture('button_clicked', {
  button_name: 'signup',
  page: 'homepage',
  timestamp: new Date().toISOString()
})

Include relevant event properties to provide context for analysis and segmentation.

When users have multiple identifiers (like anonymous ID before login), use alias() to link them:

posthog.alias('user123')

This connects the current anonymous session with the permanent user ID. Call this immediately after identifying a user for the first time to maintain session continuity.

Navigate to Activity → Live Events in your PostHog dashboard to see real-time event data. Check that:

• User identification events appear with correct IDs
• Custom events show with proper properties
• User properties are updated in person profiles

Go to People to view individual user profiles and verify data accuracy.

Set up tracking for critical user journeys and business metrics. Common events to track include:

• User registration and login
• Feature usage and interactions
• Purchase or subscription events
• Page views and navigation

Implement these systematically across your application using consistent naming and properties.