Monitoring with PostHog, Google Analytics, and Axiom

Antoine Depuydt

•April 17, 2025

Analytics

Monitoring

Performance

Next.js

TypeScript

Error Tracking

Understanding user behavior, tracking errors, and monitoring performance are essential for any production SaaS application. From PostHog for product analytics to Google Analytics for traffic insights and Axiom for server-side logging, setting up a comprehensive monitoring system requires integrating multiple services and weeks of careful development. Fastack comes with a complete, multi-provider monitoring package that handles analytics, error tracking, and logging—saving you weeks of development time.

Why comprehensive monitoring matters

Production monitoring is essential for understanding your application's health and user behavior:

Track user behavior and product usage
Identify and debug errors quickly
Monitor application performance
Make data-driven product decisions
Detect issues before users report them

What you get with Fastack

Fastack includes a complete @saas/monitoring package that provides:

PostHog product analytics

Fastack includes complete PostHog integration for product analytics:

Event tracking - Track user actions and product events
User identification - Link events to specific users
Feature flags - A/B testing and gradual rollouts
Session recordings - Watch user sessions for UX insights
Automatic pageview tracking - Track navigation automatically

import { useTrackEvent } from '@saas/monitoring/hooks';

function CheckoutButton() {
  const { trackEvent } = useTrackEvent();
  
  const handleCheckout = () => {
    trackEvent({
      name: 'checkout_started',
      properties: {
        plan: 'pro',
        price: 29.99,
      },
    });
    // ... checkout logic
  };
  
  return <button onClick={handleCheckout}>Checkout</button>;
}

Google Analytics integration

Fastack includes Google Analytics 4 (GA4) integration for web analytics:

Pageview tracking - Automatic pageview tracking on route changes
Event tracking - Track custom events and conversions
User identification - Link analytics to authenticated users
Traffic analysis - Understand user acquisition and behavior

import { MonitoringProvider } from '@saas/monitoring/components';

export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        <MonitoringProvider>
          {children}
        </MonitoringProvider>
      </body>
    </html>
  );
}

Google Analytics is automatically initialized and tracks pageviews on every route change, providing comprehensive traffic insights.

Axiom server-side logging

Fastack includes Axiom integration for structured server-side logging:

Structured logging - JSON-formatted logs with context
Log levels - DEBUG, INFO, WARN, ERROR with filtering
Request logging - Automatic request/response logging
Error tracking - Comprehensive error logging with stack traces
Context metadata - Include user ID, request path, and custom context

packages/monitoring/server/logger.ts

import { createLogger } from '@saas/monitoring/server';

export async function POST(request: Request) {
  const logger = createLogger({
    path: '/api/users',
    method: 'POST',
  });
  
  try {
    logger.request('Creating user', { email: '[email protected]' });
    // ... create user logic
    logger.success('User created', { userId: 'user_123' });
  } catch (error) {
    logger.error('Failed to create user', {}, error);
    throw error;
  }
}

All server-side logs are automatically sent to Axiom for centralized log management and analysis, making debugging production issues much easier.

Multi-provider event tracking

Fastack provides a unified event tracking system that sends events to all enabled providers simultaneously:

Single API - Track events once, sent to all enabled providers
Type-safe events - TypeScript ensures event properties are correct
Automatic provider detection - Only sends to enabled providers
Error handling - Graceful fallback if a provider fails

import { useTrackEvent } from '@saas/monitoring/hooks';

function MyComponent() {
  const { trackEvent } = useTrackEvent();
  
  // This event is automatically sent to:
  // - PostHog (if enabled)
  // - Google Analytics (if enabled)
  trackEvent({
    name: 'button_clicked',
    properties: {
      button_name: 'subscribe',
      page: '/pricing',
    },
    userId: 'user_123', // Optional: link to user
  });
}

Error tracking and debugging

Fastack provides comprehensive error tracking:

Structured error logging - Errors include stack traces and context
Request context - Errors include request path, method, and user ID
Log aggregation - All errors centralized in Axiom
Development vs production - Color-coded logs in dev, JSON in production

import { createLogger } from '@saas/monitoring/server';

export async function handler(request: Request) {
  const logger = createLogger({
    path: '/api/payment',
    method: 'POST',
    userId: 'user_123',
  });
  
  try {
    // ... payment logic
  } catch (error) {
    // Error is automatically logged with:
    // - Full stack trace
    // - Request context (path, method, userId)
    // - Custom metadata
    logger.error('Payment processing failed', {
      amount: 29.99,
      plan: 'pro',
    }, error);
    
    throw error;
  }
}

User behavior analysis

Fastack enables comprehensive user behavior tracking:

User identification - Link events to authenticated users
User properties - Track user attributes and traits
Session tracking - Understand user journeys
Conversion funnels - Track user conversion paths

import { useIdentifyUser } from '@saas/monitoring/hooks';

function UserProfile({ user }) {
  const identifyUser = useIdentifyUser();
  
  useEffect(() => {
    // Identify user in all analytics providers
    identifyUser(user.id, {
      email: user.email,
      plan: user.subscription?.plan,
      createdAt: user.createdAt,
    });
  }, [user]);
  
  return <div>...</div>;
}

Performance monitoring

Fastack includes performance monitoring capabilities:

Request logging - Track API response times and status codes
Error rates - Monitor error frequency and patterns
User activity tracking - Understand feature usage
Custom metrics - Track business-specific metrics

Cookie consent integration

Fastack respects user privacy with cookie consent integration:

GDPR compliance - Only tracks analytics if user consents
Automatic initialization - Analytics providers only initialize after consent
Server-side logging - Axiom logging works independently (no cookies)

Time saved: 25+ hours

Building monitoring and analytics from scratch typically requires:

Setting up PostHog integration (3-4 hours)
Implementing Google Analytics (2-3 hours)
Configuring Axiom logging (2-3 hours)
Building unified event tracking system (4-6 hours)
Creating structured logging utilities (3-4 hours)
Implementing error tracking (2-3 hours)
Building React hooks for tracking (2-3 hours)
Setting up cookie consent integration (2-3 hours)
Testing across all providers (2-3 hours)

Total: 22-32 hours of development time that you save with Fastack.

Best practices included

Fastack follows monitoring best practices:

Privacy-first - Respects cookie consent and user privacy
Structured logging - JSON logs in production for easy parsing
Error handling - Monitoring failures never break the app
Type safety - TypeScript ensures correct event properties
Performance - Non-blocking logging and async event tracking

Conclusion

Comprehensive monitoring and analytics are essential for understanding your application's health, user behavior, and performance. Fastack provides a complete, production-ready monitoring system that saves you weeks of development time while ensuring you have the insights needed to build and improve your SaaS product.

With Fastack, you get:

Complete PostHog integration for product analytics and feature flags
Google Analytics 4 integration for traffic and conversion tracking
Axiom integration for structured server-side logging
Unified event tracking system that sends to all enabled providers
Comprehensive error tracking with stack traces and context
Type-safe React hooks for client-side tracking
Cookie consent integration for GDPR compliance
Environment-based configuration for easy setup

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