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Alex Spinov
Alex Spinov

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PostHog Has a Free API That Gives You Product Analytics, Feature Flags, and Session Replay

PostHog is an open-source product analytics platform. Track events, feature flags, A/B tests, session recordings, and surveys — all in one tool. Self-host or use cloud.

Quick Start

npm install posthog-js
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import posthog from 'posthog-js'

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

// Track events
posthog.capture('button_clicked', { button: 'signup', page: '/pricing' })

// Identify users
posthog.identify('user-123', { name: 'John', plan: 'pro' })
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Feature Flags

// Check flag
if (posthog.isFeatureEnabled('new-dashboard')) {
  showNewDashboard()
} else {
  showOldDashboard()
}

// Flag with payload
const config = posthog.getFeatureFlagPayload('pricing-test')
// { variant: 'B', price: 29 }
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Session Replay

Enabled by default. Watch real user sessions:

  • Click heatmaps
  • Scroll depth
  • Rage clicks
  • Network requests

No extra code needed.

Free Tier

  • 1M events/month
  • 5K session recordings/month
  • Unlimited feature flags
  • Self-host: unlimited everything

PostHog vs Mixpanel vs Amplitude

Feature PostHog Mixpanel Amplitude
Open source Yes No No
Self-host Yes No No
Session replay Yes No Yes
Feature flags Yes No No
A/B tests Yes No Yes
Free tier 1M events 20M events 10M events

The Bottom Line

PostHog replaces 4-5 tools: analytics + feature flags + A/B tests + session replay + surveys. Open source, generous free tier, self-hostable.


Need to automate data collection or build custom scrapers? Check out my Apify actors for ready-made tools, or email spinov001@gmail.com for custom solutions.

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