Analytics with PostHog

Sabo includes pre-configured PostHog analytics with automatic pageview tracking, custom event support, and feature flags. PostHog is optional and only activates when environment variables are set.

Overview

PostHog is an open-source product analytics platform that helps you understand how users interact with your application. Sabo’s PostHog integration provides:

Automatic pageview tracking for all routes
Custom event tracking via the usePostHog() hook
Server-side analytics for API routes and server components
Feature flags for gradual feature rollouts
Session recording (configurable in PostHog dashboard)
Privacy-first analytics with GDPR compliance options

PostHog is completely optional. If you don’t set the environment variables, Sabo will function normally without analytics.

Need a deeper dive into every PostHog feature (insights, dashboards, cohorts)? Keep the official PostHog documentation handy while working through this guide.

Quick Setup

Create PostHog account

Visit PostHog Cloud or self-host PostHog
Create a new project
Copy your Project API Key from Project Settings
Note your PostHog host URL:
- Cloud: https://app.posthog.com (US) or https://eu.posthog.com (EU)
- Self-hosted: Your custom domain

PostHog offers a generous free tier with 1 million events per month. No credit card required for signup.

Add environment variables

Add PostHog credentials to your .env.local file:

.env.local

# PostHog Analytics (Optional)
NEXT_PUBLIC_POSTHOG_KEY=phc_your_project_api_key_here
NEXT_PUBLIC_POSTHOG_HOST=https://app.posthog.com

Important: Both variables must be present for PostHog to initialize. If either is missing, PostHog will remain disabled.

Restart your development server after adding environment variables.

Verify integration

Test that PostHog is tracking events:

Start your dev server: pnpm dev
Visit http://localhost:3000
Open browser console and look for PostHog debug messages (in development mode)
Check PostHog dashboard → Activity to see live pageviews

In development mode, PostHog automatically enables debug logging. Check your browser console for [PostHog] messages.

How It Works

Architecture

Sabo’s PostHog integration consists of three main parts:

Client-side provider (src/components/posthog-provider.tsx)
- Initializes PostHog in the browser
- Wraps the entire app to provide PostHog context
- Enables debug mode in development
Server-side client (src/lib/posthog/server.ts)
- Tracks events from API routes and server components
- Uses PostHog Node.js SDK
- Flushes events immediately for real-time tracking
Exports module (src/lib/posthog/index.ts)
- Centralizes imports for both client and server utilities
- Re-exports usePostHog hook and getPostHogClient function

Initialization

PostHog initializes automatically when the app loads, but only if environment variables are set.

src/components/posthog-provider.tsx

"use client";

import posthog from "posthog-js";
import { PostHogProvider } from "posthog-js/react";

if (typeof window !== "undefined") {
  const posthogKey = process.env.NEXT_PUBLIC_POSTHOG_KEY;
  const posthogHost = process.env.NEXT_PUBLIC_POSTHOG_HOST;

  if (posthogKey && posthogHost) {
    posthog.init(posthogKey, {
      api_host: posthogHost,
      loaded: (posthog) => {
        if (process.env.NODE_ENV === "development") {
          posthog.debug();  // Enable debug logging in dev
        }
      },
    });
  }
}

export function PHProvider({ children }: { children: React.ReactNode }) {
  return <PostHogProvider client={posthog}>{children}</PostHogProvider>;
}

The PHProvider wraps your entire app in src/app/layout.tsx:

src/app/layout.tsx

import { PHProvider } from "@/components/posthog-provider";

export default function RootLayout({ children }) {
  return (
    <html lang="en">
      <body>
        <PHProvider>
          <ThemeProvider>
            {children}
          </ThemeProvider>
        </PHProvider>
      </body>
    </html>
  );
}

PHProvider wraps ThemeProvider to ensure PostHog context is available throughout the entire application, including all client components.

Tracking Events

Automatic Pageview Tracking

PostHog automatically tracks pageviews for all routes in your app. No additional code required. What’s tracked:

Route changes (including Next.js App Router navigation)
URL parameters and query strings
Referrer information
Browser and device details

Viewing pageviews:

Go to PostHog Dashboard → Activity
Filter by event type: $pageview
See real-time page visits with full URL paths

Custom Event Tracking (Client-Side)

Track user interactions, button clicks, form submissions, and other custom events using the usePostHog() hook.

Import the hook

import { usePostHog } from "@/lib/posthog";

Call the hook in your component

export function MyComponent() {
  const posthog = usePostHog();
  
  // Component logic...
}

Track events

const handleClick = () => {
  // Track event with properties
  posthog?.capture("button_clicked", {
    button_name: "upgrade_to_pro",
    location: "pricing_page",
    plan: "pro",
  });
};

Complete Example

src/components/marketing/pricing.tsx

"use client";

import { usePostHog } from "@/lib/posthog";
import { Button } from "@/components/ui/button";

export function PricingCard({ plan }) {
  const posthog = usePostHog();
  
  const handleUpgrade = () => {
    // Track subscription initiation
    posthog?.capture("subscription_started", {
      plan_id: plan.id,
      plan_name: plan.name,
      price: plan.monthlyPrice,
      billing_cycle: "monthly",
    });
    
    // Proceed with checkout...
  };
  
  return (
    <Button onClick={handleUpgrade}>
      Upgrade to {plan.name}
    </Button>
  );
}

Use optional chaining (posthog?.capture) to safely handle cases where PostHog is not initialized (e.g., missing environment variables).

Common Events to Track

Here are some recommended events to track in a SaaS application:

// User actions
posthog?.capture("user_signed_up", { method: "email" });
posthog?.capture("user_logged_in", { method: "google_oauth" });
posthog?.capture("user_logged_out");

// Subscription events
posthog?.capture("subscription_started", { plan: "pro", cycle: "yearly" });
posthog?.capture("subscription_cancelled", { reason: "too_expensive" });
posthog?.capture("subscription_upgraded", { from: "free", to: "pro" });

// Feature usage
posthog?.capture("feature_used", { feature_name: "dashboard_export" });
posthog?.capture("search_performed", { query: "analytics", results_count: 12 });
posthog?.capture("file_uploaded", { file_type: "pdf", file_size: 2048 });

// Engagement
posthog?.capture("form_submitted", { form_name: "contact", success: true });
posthog?.capture("video_watched", { video_id: "onboarding", duration: 180 });
posthog?.capture("invite_sent", { invite_count: 3 });

Server-Side Event Tracking

Track events from API routes, server actions, or server components using the server-side PostHog client.

src/app/api/your-route/route.ts

import { getPostHogClient } from "@/lib/posthog";

export async function POST(request: Request) {
  const posthog = getPostHogClient();
  
  // Track server-side event
  posthog?.capture({
    distinctId: userId,  // User identifier
    event: "api_call_made",
    properties: {
      endpoint: "/api/data",
      method: "POST",
      response_time: 142,
    },
  });
  
  // Your API logic...
  
  return Response.json({ success: true });
}

The server client (src/lib/posthog/server.ts) is configured to flush events immediately:

src/lib/posthog/server.ts

import { PostHog } from "posthog-node";

let posthogClient: PostHog | null = null;

export function getPostHogClient(): PostHog | null {
  const posthogKey = process.env.NEXT_PUBLIC_POSTHOG_KEY;
  const posthogHost = process.env.NEXT_PUBLIC_POSTHOG_HOST;

  if (!posthogKey || !posthogHost) {
    return null;  // PostHog disabled
  }

  if (!posthogClient) {
    posthogClient = new PostHog(posthogKey, {
      host: posthogHost,
      flushAt: 1,           // Flush after each event
      flushInterval: 0,     // Don't batch events
    });
  }
  
  posthogClient.debug(true);  // Enable debug logging
  return posthogClient;
}

Server-side tracking requires a distinctId (usually the user ID) to associate events with specific users. Make sure to provide this when capturing server events.

User Identification

Identifying Users

Call posthog.identify() in whichever component completes your authentication flow (for example, the /sign-in page) so future events are tied to the logged-in user:

"use client";

import { usePostHog } from "@/lib/posthog";

export function SignInForm() {
  const posthog = usePostHog();
  
  const handleSignIn = async (email: string) => {
    const user = await signIn(email); // Your existing auth logic
    
    posthog?.identify(user.id, {
      email: user.email,
      name: user.full_name,
      plan: "free",
      created_at: user.created_at,
    });
    
    posthog?.capture("user_signed_in", { method: "email" });
  };
}

Setting User Properties

Update user properties as they change:

// Update subscription status
posthog?.people.set({
  plan: "pro",
  mrr: 12,
  billing_cycle: "monthly",
});

// Track trait changes
posthog?.capture("subscription_upgraded", {
  from_plan: "free",
  to_plan: "pro",
});

Resetting User Identity

Clear user identification on logout:

const handleLogout = async () => {
  await signOut();
  
  // Reset PostHog identity
  posthog?.reset();
};

Feature Flags

PostHog feature flags allow you to roll out features gradually, run A/B tests, and toggle features without deploying code.

Using Feature Flags (Client-Side)

"use client";

import { usePostHog } from "@/lib/posthog";
import { useEffect, useState } from "react";

export function NewFeature() {
  const posthog = usePostHog();
  const [showNewUI, setShowNewUI] = useState(false);
  
  useEffect(() => {
    // Check feature flag value
    const isEnabled = posthog?.isFeatureEnabled("new-dashboard-ui");
    setShowNewUI(isEnabled ?? false);
  }, [posthog]);
  
  return showNewUI ? <NewDashboard /> : <OldDashboard />;
}

Feature Flag with Variants

const variant = posthog?.getFeatureFlag("pricing-experiment");

// Show different pricing based on variant
if (variant === "high-price") {
  return <PricingCard price={29} />;
} else if (variant === "low-price") {
  return <PricingCard price={19} />;
} else {
  return <PricingCard price={24} />;  // Default
}

Creating Feature Flags

Go to PostHog Dashboard → Feature Flags
Click “New feature flag”
Configure:
- Key: new-dashboard-ui (use in code)
- Rollout: Percentage (e.g., 50% of users)
- Filters: Target specific users, groups, or properties
Save and the flag is immediately available

Feature flags are cached locally, so changes may take a few minutes to propagate to all users. You can force a refresh by calling posthog?.reloadFeatureFlags().

Want to convert those flags into statistically sound experiments? PostHog’s A/B testing guide explains how to define variants, success metrics, and rollouts using the same flag keys shown above.

Configuration Options

PostHog Initialization Options

You can customize PostHog behavior by modifying src/components/posthog-provider.tsx:

src/components/posthog-provider.tsx

posthog.init(posthogKey, {
  api_host: posthogHost,
  
  // Session recording (default: disabled)
  disable_session_recording: false,
  
  // Autocapture clicks and form submissions (default: true)
  autocapture: true,
  
  // Capture pageviews automatically (default: true)
  capture_pageview: true,
  
  // Capture pageleave events (default: true)
  capture_pageleave: true,
  
  // Respect Do Not Track browser setting (default: false)
  respect_dnt: true,
  
  // Debug mode (automatically enabled in development)
  loaded: (posthog) => {
    if (process.env.NODE_ENV === "development") {
      posthog.debug();
    }
  },
});

Privacy Options

Configure PostHog to respect user privacy:

// Disable session recording for sensitive pages
useEffect(() => {
  if (window.location.pathname.includes("/settings/account")) {
    posthog?.stopSessionRecording();
  }
}, [posthog]);

// Opt user out of tracking
posthog?.opt_out_capturing();

// Opt user back in
posthog?.opt_in_capturing();

// Check if user has opted out
const hasOptedOut = posthog?.has_opted_out_capturing();

Best Practices

If you need a formal naming taxonomy for events and properties, refer to PostHog’s event taxonomy guide. It includes naming tables, spreadsheet templates, and enforcement strategies that complement the recommendations below.

1. Event Naming Conventions

Use consistent, descriptive names for events:Good:

subscription_started
user_signed_up
file_uploaded

Bad:

click
event1
test

Guidelines:

Use snake_case for event names
Use past tense verbs (clicked, not click)
Be specific (checkout_completed vs purchase)
Group related events with prefixes (subscription_*, user_*)

2. Event Properties

Include relevant context with every event:

posthog?.capture("file_uploaded", {
  file_type: "pdf",           // What kind
  file_size: 2048,            // How large
  upload_method: "drag_drop", // How uploaded
  location: "dashboard",      // Where
  timestamp: Date.now(),      // When
});

Guidelines:

Keep property names consistent across events
Include user properties (plan, role, etc.)
Add context (page location, user state)
Use appropriate data types (numbers for counts, booleans for flags)

3. Performance Optimization

PostHog batches events by default, but you can optimize further:

// Debounce high-frequency events
const debouncedTrack = debounce((searchTerm) => {
  posthog?.capture("search_performed", { query: searchTerm });
}, 500);

// Track only on significant actions
const handleScroll = () => {
  if (scrollPercent > 75 && !tracked) {
    posthog?.capture("article_read_75_percent");
    setTracked(true);
  }
};

Tips:

Don’t track every keystroke or mouse movement
Batch similar events (e.g., track scroll milestones: 25%, 50%, 75%, 100%)
Use feature flags to disable analytics in staging environments

4. Testing Analytics

Verify events are tracked correctly:In Development:

Check browser console for [PostHog] debug messages
Visit PostHog Dashboard → Activity (live view)
Use PostHog’s “Test mode” to see events in real-time

Before Production:

Test with different user states (logged in/out, different plans)
Verify user identification works after sign-in
Check that properties contain expected values
Test feature flags with different rollout percentages

// Add logging in development
if (process.env.NODE_ENV === "development") {
  console.log("Tracking event:", eventName, properties);
}
posthog?.capture(eventName, properties);

Production Deployment

Update environment variables

Set PostHog credentials in your production environment (Vercel, Netlify, etc.):

NEXT_PUBLIC_POSTHOG_KEY=phc_your_production_key
NEXT_PUBLIC_POSTHOG_HOST=https://app.posthog.com

Use separate PostHog projects for development and production to keep analytics data isolated.

Disable debug mode

Ensure debug mode is only enabled in development (already configured in posthog-provider.tsx):

loaded: (posthog) => {
  if (process.env.NODE_ENV === "development") {
    posthog.debug();  // Only in dev
  }
}

Configure session recording

Decide whether to enable session recording in PostHog Dashboard:

Go to Settings → Project Settings → Recordings
Enable/disable session recording
Configure privacy settings:
- Mask sensitive inputs (passwords, credit cards)
- Block specific elements by CSS selector
- Disable recording on certain pages

Session recording captures user interactions. Ensure you comply with GDPR/privacy regulations and disclose this in your privacy policy.

Set up alerts

Configure PostHog to notify you of important events:

Go to Alerts → Create alert
Choose trigger (e.g., “Subscription cancelled” event)
Set threshold and frequency
Connect to Slack, email, or webhooks

Test alerts in PostHog to ensure notifications are working before going live.

Troubleshooting

PostHog not initializing

Symptoms: No events in PostHog dashboard, no debug messages in console.Causes:

Missing environment variables
Incorrect API key or host
Variables not prefixed with NEXT_PUBLIC_

Fix:

Verify both NEXT_PUBLIC_POSTHOG_KEY and NEXT_PUBLIC_POSTHOG_HOST are set in .env.local
Restart dev server after adding variables
Check browser console for PostHog errors
Confirm API key format: phc_...
Use correct host (US: https://app.posthog.com, EU: https://eu.posthog.com)

Events not appearing in dashboard

Symptoms: PostHog initializes but events don’t show up.Causes:

Wrong project API key
Ad blockers blocking PostHog
Network issues
PostHog ingestion delay

Fix:

Check you’re viewing the correct project in PostHog dashboard
Disable ad blockers (uBlock, Privacy Badger often block analytics)
Check browser network tab for failed requests to PostHog
Wait 1-2 minutes for events to appear (PostHog has slight delay)
Verify API key in PostHog → Project Settings → Project API Key

'usePostHog is not a function' error

Symptoms: React error when calling usePostHog().Causes:

Missing "use client" directive
Component is server component
PostHog not imported correctly

Fix:

Add "use client" at top of file using usePostHog()
Import from @/lib/posthog, not posthog-js directly
Ensure PHProvider wraps your component tree in layout.tsx

"use client";  // Add this!

import { usePostHog } from "@/lib/posthog";  // Correct import

export function MyComponent() {
  const posthog = usePostHog();
  // ...
}

Server-side tracking not working

Symptoms: getPostHogClient() returns null on server.Causes:

Environment variables not set in production
Variables missing NEXT_PUBLIC_ prefix

Fix:

Verify environment variables are set in hosting platform (Vercel, Netlify)
Both client and server use NEXT_PUBLIC_* variables (this is intentional for consistency)
Redeploy after adding environment variables
Check server logs for PostHog initialization messages

Feature flags always return false

Symptoms: isFeatureEnabled() always returns false.Causes:

Feature flag not created in PostHog
User not identified (posthog.identify() not called)
Flag filters don’t match current user
Feature flags not loaded yet

Fix:

Create feature flag in PostHog Dashboard → Feature Flags
Call posthog.identify(userId) after authentication
Check flag filters/rollout percentage
Wait for flags to load or call posthog.reloadFeatureFlags()

useEffect(() => {
  // Wait for feature flags to load
  posthog?.onFeatureFlags(() => {
    const isEnabled = posthog.isFeatureEnabled("flag-name");
    setShowFeature(isEnabled);
  });
}, [posthog]);

PostHog provides tools to help you comply with privacy regulations: PostHog sets cookies (ph_*) to track users. Implement cookie consent before initializing:

src/components/posthog-provider.tsx

if (typeof window !== "undefined") {
  // Check for user consent before initializing
  const hasConsent = getCookieConsent(); // Your consent logic
  
  if (hasConsent && posthogKey && posthogHost) {
    posthog.init(posthogKey, {
      api_host: posthogHost,
      // ...
    });
  }
}

Data Deletion Requests

Handle GDPR deletion requests via PostHog API:

// In your data deletion API route
await fetch(`https://app.posthog.com/api/persons/${userId}`, {
  method: 'DELETE',
  headers: {
    'Authorization': `Bearer ${process.env.POSTHOG_PERSONAL_API_KEY}`
  }
});

Anonymization

Anonymize sensitive data before tracking:

// Don't track PII directly
posthog?.capture("form_submitted", {
  email_domain: email.split("@")[1],  // Only domain
  user_id_hash: hashUserId(userId),   // Hash instead of raw ID
});

Review your privacy policy to disclose PostHog usage. Sabo includes placeholder legal pages in src/content/legal/ that mention PostHog—update these with your specific implementation.

Getting Started.

Customization Guides

UI Components

Core Features

Deployment

API Reference

Analytics with PostHog

Overview

Quick Setup

How It Works

Architecture

Initialization

Tracking Events

Automatic Pageview Tracking

Custom Event Tracking (Client-Side)

Complete Example

Common Events to Track

Server-Side Event Tracking

User Identification

Identifying Users

Setting User Properties

Resetting User Identity

Feature Flags

Using Feature Flags (Client-Side)

Feature Flag with Variants

Creating Feature Flags

Configuration Options

PostHog Initialization Options

Privacy Options

Best Practices

Production Deployment

Troubleshooting

Data Deletion Requests

Anonymization

Getting Started.

Customization Guides

UI Components

Core Features

Deployment

API Reference

​Overview

​Quick Setup

​How It Works

​Architecture

​Initialization

​Tracking Events

​Automatic Pageview Tracking

​Custom Event Tracking (Client-Side)

​Complete Example

​Common Events to Track

​Server-Side Event Tracking

​User Identification

​Identifying Users

​Setting User Properties

​Resetting User Identity

​Feature Flags

​Using Feature Flags (Client-Side)

​Feature Flag with Variants

​Creating Feature Flags

​Configuration Options

​PostHog Initialization Options

​Privacy Options

​Best Practices

​Production Deployment

​Troubleshooting

​Privacy & GDPR Compliance

​Cookie Consent

​Data Deletion Requests

​Anonymization

Overview

Quick Setup

How It Works

Architecture

Initialization

Tracking Events

Automatic Pageview Tracking

Custom Event Tracking (Client-Side)

Complete Example

Common Events to Track

Server-Side Event Tracking

User Identification

Identifying Users

Setting User Properties

Resetting User Identity

Feature Flags

Using Feature Flags (Client-Side)

Feature Flag with Variants

Creating Feature Flags

Configuration Options

PostHog Initialization Options

Privacy Options

Best Practices

Production Deployment

Troubleshooting

Privacy & GDPR Compliance

Cookie Consent

Data Deletion Requests

Anonymization