PostHog: Complete Product Analytics Guide

What Is PostHog

PostHog is an open source product analytics platform that helps product and growth teams understand how users interact with their application or website. Unlike closed tools such as Google Analytics or Mixpanel, PostHog offers the option to self-host the entire infrastructure, keeping full control over your data.

The platform combines multiple capabilities into a single product: event analytics, session replay, feature flags, A/B testing, and surveys. This removes the need to subscribe to several independent tools and simplifies technical integration.

Core Features

Event analytics

PostHog captures events automatically (autocapture) without manual instrumentation. Every click, pageview, or form submission is recorded from the very start. For more advanced analysis, you can define custom events that reflect business actions: subscriptions, purchases, or feature activations.

Session replay

Session recordings show exactly what each user does: where they click, how long they stay in each section, and where they drop off. Combined with conversion funnels, you can pinpoint the exact moment of friction and watch the real user behavior at that step.

Feature flags and A/B testing

PostHog includes a native feature flag system that lets you roll out features gradually to a percentage of users. This integrates directly with the experimentation module (A/B testing), allowing you to measure the impact of each change on conversion metrics before a full rollout.

In-app surveys

Surveys let you collect qualitative feedback directly within the product. You can target surveys by cohort, previous behavior, or user properties to gather relevant data without disrupting the experience.

PostHog vs Alternatives

Feature	PostHog	Mixpanel	Amplitude	GA4
Open source	Yes	No	No	No
Self-hosting	Yes	No	No	No
Session replay	Yes	No	Limited	No
Feature flags	Yes	No	Yes	No
A/B testing	Yes	No	Yes	Limited
Entry price	Free	Free	Free	Free
Free tier limit	1M events	20M events	50M events	Unlimited

PostHog's main advantage is consolidation: instead of combining GA4 + Hotjar + LaunchDarkly + Optimizely, you get everything in a single platform with a unified data model.

How to Set Up PostHog

Cloud installation

The fastest way is to use PostHog Cloud. Create an account at posthog.com, grab your project API key, and install the snippet on your site:

<script>
  !function(t,e){var o,n,p,r;e.__SV||(window.posthog=e,e._i=[],e.init=function(i,s,a){function g(t,e){var o=e.split(".");2==o.length&&(t=t[o[0]],e=o[1]),t[e]=function(){t.push([e].concat(Array.prototype.slice.call(arguments,0)))}}(p=t.createElement("script")).type="text/javascript",p.crossOrigin="anonymous",p.async=!0,p.src=s.api_host+"/static/array.js",(r=t.getElementsByTagName("script")[0]).parentNode.insertBefore(p,r);var u=e;for(void 0!==a?u=e[a]=[]:a="posthog",u.people=u.people||[],u.toString=function(t){var e="posthog";return"posthog"!==a&&(e+="."+a),t||(e+=" (stub)"),e},u.people.toString=function(){return u.toString(1)+".people (stub)"},o="init capture register register_once register_for_session unregister opt_in_capturing opt_out_capturing has_opted_in_capturing has_opted_out_capturing reset isFeatureEnabled onFeatureFlags getFeatureFlag getFeatureFlagPayload reloadFeatureFlags group identify setPersonProperties setGroupProperties".split(" "),n=0;n<o.length;n++)g(u,o[n]);e._i.push([i,s,a])},e.__SV=1)}(document,window.posthog||[]);
  posthog.init('YOUR_API_KEY',{api_host:'https://eu.i.posthog.com'})
</script>

Custom events

Beyond autocapture, define events that reflect your conversion funnel:

posthog.capture('purchase_completed', {
  product_id: 'SKU-123',
  value: 49.99,
  currency: 'EUR'
})

Funnels and retention

Once data is flowing, create funnels to visualize conversion rates between steps. PostHog automatically calculates drop-off rates and lets you break down by user properties (device, country, acquisition cohort).

CRO Use Cases

PostHog is especially useful in three optimization scenarios:

1. Diagnosing broken funnels. Combine funnel analytics with session replay to see exactly what users do when they drop off at each step. No guessing needed: you watch real behavior.

2. Validating hypotheses with A/B testing. Launch an experiment directly from PostHog, segment traffic, and measure the impact on your north star metric. All without external tools.

3. Personalization with feature flags. Activate features only for specific segments and measure whether they improve conversion before a full rollout.

Limitations to Consider

PostHog is not perfect for every case. Autocapture can generate noise on sites with many interactive elements. Self-hosting requires infrastructure (ClickHouse + PostgreSQL) that can be expensive to maintain. And the learning curve is steeper than more visual tools like Hotjar.

For small teams without DevOps resources, PostHog Cloud on its free tier is the best entry point. For companies with strict privacy requirements (GDPR, EU data residency), self-hosting or EU-region hosting are decisive advantages.

Conclusion

PostHog represents a paradigm shift in product analytics: instead of paying for multiple fragmented tools, you consolidate analytics, session replay, A/B testing, and feature flags into a single platform. For CRO-focused teams, this means faster experimentation cycles and more connected data.

If you want to apply product analytics to your conversion strategy, at Boost we help teams set up their analytics stack and design experimentation processes that drive results. You can also audit your site for free with Scan&Boost.

Adrià Vidal — Boost