Custom Event Tracking: GA4, Mixpanel & Amplitude Integration

Last Updated: December 25, 2026 | Reading Time: 12 minutes

Introduction: Why Custom Events Are Critical for ChatGPT Apps

When building ChatGPT applications with MakeAIHQ.com, understanding user behavior goes far beyond pageviews and sessions. Custom event tracking reveals how users interact with your conversational interface: which prompts they use, where they drop off in multi-turn conversations, which tools they invoke most frequently, and which features drive conversions.

Unlike traditional web analytics that track page loads and clicks, ChatGPT apps require event-driven analytics that capture:

Conversational patterns: Message sequences, prompt refinements, context switches
Tool invocations: Which MCP server tools users call and why
Widget interactions: Button clicks, form submissions, state changes within cards
Conversion funnels: User journey from first message to paid subscription
Performance metrics: Response times, error rates, token consumption

Without custom event tracking, you're flying blind. You might see that 1,000 users opened your ChatGPT app, but you won't know which 10 users completed a purchase, which feature caused 200 users to abandon the conversation, or why your Professional tier converts 3x better than Starter.

In this comprehensive guide, we'll implement production-ready custom event tracking across three major analytics platforms: Google Analytics 4 (GA4), Mixpanel, and Amplitude. You'll learn how to track conversational events, user properties, conversion funnels, and debug analytics implementations for ChatGPT apps built with MakeAIHQ's no-code platform.

GA4 Event Tracking: The Foundation

Google Analytics 4 (GA4) is the most widely used analytics platform, offering free tier support for up to 10 million events per month. For ChatGPT apps, GA4 excels at tracking high-level user journeys, conversion funnels, and acquisition channels.

Why GA4 for ChatGPT Apps?

Free tier: 10M events/month (sufficient for early-stage apps)
BigQuery integration: Export raw event data for custom analysis
Recommended events: Pre-built event schemas for common actions
Cross-platform tracking: Web, iOS, Android (if you expand beyond ChatGPT)
Google Search Console integration: See which keywords drive ChatGPT app installs

GA4 Event Structure

GA4 events consist of:

Event name: Required (e.g., chatgpt_message_sent, tool_invoked)
Event parameters: Optional key-value pairs (e.g., {message_length: 42, user_tier: 'professional'})
User properties: Persistent attributes (e.g., {subscription_tier: 'pro', first_app_created: '2026-12-15'})

Production-Ready GA4 Event Tracker

Here's a TypeScript implementation that handles offline queuing, automatic retry, and debug logging:

// lib/analytics/ga4-tracker.ts
/**
 * Production-ready GA4 event tracker for ChatGPT apps
 *
 * Features:
 * - Offline event queuing
 * - Automatic retry with exponential backoff
 * - Debug mode for development
 * - Type-safe event definitions
 * - User property management
 */

import { v4 as uuidv4 } from 'uuid';

interface GA4Config {
  measurementId: string;
  apiSecret: string;
  debug?: boolean;
}

interface GA4Event {
  name: string;
  params?: Record<string, string | number | boolean>;
}

interface GA4UserProperty {
  [key: string]: {
    value: string | number | boolean;
  };
}

class GA4Tracker {
  private config: GA4Config;
  private clientId: string;
  private userId?: string;
  private eventQueue: GA4Event[] = [];
  private isOnline: boolean = true;
  private retryAttempts: Map<string, number> = new Map();

  constructor(config: GA4Config) {
    this.config = config;
    this.clientId = this.getOrCreateClientId();
    this.setupOfflineDetection();
  }

  /**
   * Track a custom event
   */
  async trackEvent(name: string, params?: Record<string, any>): Promise<void> {
    const event: GA4Event = {
      name,
      params: {
        ...params,
        timestamp: Date.now(),
        session_id: this.getSessionId(),
      },
    };

    if (this.config.debug) {
      console.log('[GA4] Event:', event);
    }

    if (!this.isOnline) {
      this.eventQueue.push(event);
      return;
    }

    try {
      await this.sendEvent(event);
    } catch (error) {
      console.error('[GA4] Failed to send event:', error);
      this.eventQueue.push(event);
      this.scheduleRetry();
    }
  }

  /**
   * Set user ID (for authenticated users)
   */
  setUserId(userId: string): void {
    this.userId = userId;
    if (this.config.debug) {
      console.log('[GA4] User ID set:', userId);
    }
  }

  /**
   * Set user properties
   */
  async setUserProperties(properties: Record<string, any>): Promise<void> {
    const userProperties: GA4UserProperty = {};

    for (const [key, value] of Object.entries(properties)) {
      userProperties[key] = { value };
    }

    await this.sendRequest({
      user_properties: userProperties,
    });
  }

  /**
   * Track ChatGPT-specific events
   */
  async trackChatGPTEvent(eventType: string, data?: Record<string, any>): Promise<void> {
    const eventMap: Record<string, string> = {
      message_sent: 'chatgpt_message_sent',
      tool_invoked: 'chatgpt_tool_invoked',
      widget_rendered: 'chatgpt_widget_rendered',
      conversation_started: 'chatgpt_conversation_started',
      conversation_ended: 'chatgpt_conversation_ended',
      error_occurred: 'chatgpt_error_occurred',
    };

    const eventName = eventMap[eventType] || `chatgpt_${eventType}`;
    await this.trackEvent(eventName, data);
  }

  /**
   * Send event to GA4 Measurement Protocol
   */
  private async sendEvent(event: GA4Event): Promise<void> {
    const payload = {
      client_id: this.clientId,
      user_id: this.userId,
      events: [event],
    };

    await this.sendRequest(payload);
  }

  /**
   * Send request to GA4 API
   */
  private async sendRequest(payload: any): Promise<void> {
    const endpoint = this.config.debug
      ? 'https://www.google-analytics.com/debug/mp/collect'
      : 'https://www.google-analytics.com/mp/collect';

    const url = `${endpoint}?measurement_id=${this.config.measurementId}&api_secret=${this.config.apiSecret}`;

    const response = await fetch(url, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify(payload),
    });

    if (!response.ok) {
      const error = await response.text();
      throw new Error(`GA4 API error: ${error}`);
    }

    if (this.config.debug) {
      const result = await response.json();
      console.log('[GA4] Validation result:', result);
    }
  }

  /**
   * Get or create client ID
   */
  private getOrCreateClientId(): string {
    const key = 'ga4_client_id';
    let clientId = localStorage.getItem(key);

    if (!clientId) {
      clientId = uuidv4();
      localStorage.setItem(key, clientId);
    }

    return clientId;
  }

  /**
   * Get or create session ID
   */
  private getSessionId(): string {
    const key = 'ga4_session_id';
    const sessionTimeout = 30 * 60 * 1000; // 30 minutes

    const stored = localStorage.getItem(key);
    if (stored) {
      const { id, timestamp } = JSON.parse(stored);
      if (Date.now() - timestamp < sessionTimeout) {
        return id;
      }
    }

    const sessionId = uuidv4();
    localStorage.setItem(key, JSON.stringify({
      id: sessionId,
      timestamp: Date.now(),
    }));

    return sessionId;
  }

  /**
   * Setup offline detection
   */
  private setupOfflineDetection(): void {
    window.addEventListener('online', () => {
      this.isOnline = true;
      this.flushQueue();
    });

    window.addEventListener('offline', () => {
      this.isOnline = false;
    });
  }

  /**
   * Flush event queue
   */
  private async flushQueue(): Promise<void> {
    while (this.eventQueue.length > 0) {
      const event = this.eventQueue.shift();
      if (event) {
        try {
          await this.sendEvent(event);
        } catch (error) {
          console.error('[GA4] Failed to flush event:', error);
          this.eventQueue.unshift(event);
          break;
        }
      }
    }
  }

  /**
   * Schedule retry with exponential backoff
   */
  private scheduleRetry(): void {
    const queueKey = 'event_queue';
    const attempts = this.retryAttempts.get(queueKey) || 0;
    const delay = Math.min(1000 * Math.pow(2, attempts), 30000); // Max 30s

    setTimeout(() => {
      this.flushQueue();
      this.retryAttempts.set(queueKey, attempts + 1);
    }, delay);
  }
}

// Export singleton instance
export const ga4 = new GA4Tracker({
  measurementId: process.env.GA4_MEASUREMENT_ID!,
  apiSecret: process.env.GA4_API_SECRET!,
  debug: process.env.NODE_ENV === 'development',
});

// Convenience methods
export const trackEvent = (name: string, params?: Record<string, any>) => {
  return ga4.trackEvent(name, params);
};

export const setUserId = (userId: string) => {
  ga4.setUserId(userId);
};

export const setUserProperties = (properties: Record<string, any>) => {
  return ga4.setUserProperties(properties);
};

export const trackChatGPTEvent = (eventType: string, data?: Record<string, any>) => {
  return ga4.trackChatGPTEvent(eventType, data);
};

Usage Example

// Track message sent
await trackChatGPTEvent('message_sent', {
  message_length: 42,
  tool_invoked: false,
  conversation_turn: 3,
});

// Track tool invocation
await trackChatGPTEvent('tool_invoked', {
  tool_name: 'create_booking',
  tool_parameters: JSON.stringify({ date: '2026-12-25', time: '10:00' }),
  execution_time_ms: 320,
});

// Set user properties
await setUserProperties({
  subscription_tier: 'professional',
  first_app_created: '2026-12-15',
  total_apps: 5,
});

Mixpanel Integration: Deep User Insights

Mixpanel is designed for product analytics, offering powerful funnel analysis, cohort tracking, and user journey visualization. It's ideal for understanding how users progress through your ChatGPT app's conversion funnel.

Why Mixpanel for ChatGPT Apps?

User-centric tracking: Events tied to user profiles (not sessions)
Funnel analysis: Visualize conversion paths (message → tool → payment)
Cohort analysis: Compare user segments (free vs. paid, fitness vs. restaurant)
Real-time dashboards: Monitor conversions as they happen
A/B testing integration: Track experiment variants

Production-Ready Mixpanel Integration

// lib/analytics/mixpanel-tracker.ts
/**
 * Production-ready Mixpanel integration for ChatGPT apps
 *
 * Features:
 * - User profile management
 * - Incremental properties
 * - Funnel tracking
 * - Revenue tracking
 * - Group analytics (for B2B apps)
 */

import mixpanel from 'mixpanel-browser';

interface MixpanelConfig {
  token: string;
  debug?: boolean;
  trackAutomaticEvents?: boolean;
}

class MixpanelTracker {
  private config: MixpanelConfig;
  private initialized: boolean = false;

  constructor(config: MixpanelConfig) {
    this.config = config;
    this.initialize();
  }

  /**
   * Initialize Mixpanel
   */
  private initialize(): void {
    mixpanel.init(this.config.token, {
      debug: this.config.debug,
      track_pageview: this.config.trackAutomaticEvents ?? true,
      persistence: 'localStorage',
      ignore_dnt: false,
    });

    this.initialized = true;

    if (this.config.debug) {
      console.log('[Mixpanel] Initialized');
    }
  }

  /**
   * Track event
   */
  trackEvent(eventName: string, properties?: Record<string, any>): void {
    if (!this.initialized) {
      console.error('[Mixpanel] Not initialized');
      return;
    }

    mixpanel.track(eventName, {
      ...properties,
      timestamp: new Date().toISOString(),
      platform: 'chatgpt',
    });

    if (this.config.debug) {
      console.log('[Mixpanel] Event tracked:', eventName, properties);
    }
  }

  /**
   * Identify user
   */
  identify(userId: string): void {
    mixpanel.identify(userId);

    if (this.config.debug) {
      console.log('[Mixpanel] User identified:', userId);
    }
  }

  /**
   * Set user profile properties
   */
  setUserProfile(properties: Record<string, any>): void {
    mixpanel.people.set(properties);

    if (this.config.debug) {
      console.log('[Mixpanel] User profile updated:', properties);
    }
  }

  /**
   * Set user profile properties (once)
   */
  setUserProfileOnce(properties: Record<string, any>): void {
    mixpanel.people.set_once(properties);
  }

  /**
   * Increment numeric property
   */
  incrementProperty(property: string, value: number = 1): void {
    mixpanel.people.increment(property, value);

    if (this.config.debug) {
      console.log(`[Mixpanel] Incremented ${property} by ${value}`);
    }
  }

  /**
   * Track revenue
   */
  trackRevenue(amount: number, properties?: Record<string, any>): void {
    mixpanel.people.track_charge(amount, properties);

    if (this.config.debug) {
      console.log('[Mixpanel] Revenue tracked:', amount, properties);
    }
  }

  /**
   * Track ChatGPT conversation funnel
   */
  trackConversationFunnel(step: string, properties?: Record<string, any>): void {
    const funnelSteps = {
      started: 'Conversation Started',
      message_sent: 'Message Sent',
      tool_invoked: 'Tool Invoked',
      widget_rendered: 'Widget Rendered',
      action_completed: 'Action Completed',
    };

    const eventName = funnelSteps[step as keyof typeof funnelSteps] || step;
    this.trackEvent(eventName, {
      ...properties,
      funnel: 'chatgpt_conversation',
    });
  }

  /**
   * Track subscription funnel
   */
  trackSubscriptionFunnel(step: string, properties?: Record<string, any>): void {
    const funnelSteps = {
      pricing_viewed: 'Pricing Page Viewed',
      plan_selected: 'Plan Selected',
      checkout_started: 'Checkout Started',
      payment_info_entered: 'Payment Info Entered',
      subscription_completed: 'Subscription Completed',
    };

    const eventName = funnelSteps[step as keyof typeof funnelSteps] || step;
    this.trackEvent(eventName, {
      ...properties,
      funnel: 'subscription',
    });
  }

  /**
   * Create user alias (for pre-signup tracking)
   */
  alias(newId: string): void {
    mixpanel.alias(newId);

    if (this.config.debug) {
      console.log('[Mixpanel] User alias created:', newId);
    }
  }

  /**
   * Reset user (on logout)
   */
  reset(): void {
    mixpanel.reset();

    if (this.config.debug) {
      console.log('[Mixpanel] User reset');
    }
  }

  /**
   * Track time for event
   */
  timeEvent(eventName: string): void {
    mixpanel.time_event(eventName);
  }

  /**
   * Register super properties (sent with every event)
   */
  registerSuperProperties(properties: Record<string, any>): void {
    mixpanel.register(properties);

    if (this.config.debug) {
      console.log('[Mixpanel] Super properties registered:', properties);
    }
  }
}

// Export singleton instance
export const mixpanelTracker = new MixpanelTracker({
  token: process.env.MIXPANEL_TOKEN!,
  debug: process.env.NODE_ENV === 'development',
  trackAutomaticEvents: true,
});

// Convenience methods
export const trackEvent = (eventName: string, properties?: Record<string, any>) => {
  mixpanelTracker.trackEvent(eventName, properties);
};

export const identify = (userId: string) => {
  mixpanelTracker.identify(userId);
};

export const setUserProfile = (properties: Record<string, any>) => {
  mixpanelTracker.setUserProfile(properties);
};

export const trackConversationFunnel = (step: string, properties?: Record<string, any>) => {
  mixpanelTracker.trackConversationFunnel(step, properties);
};

export const trackSubscriptionFunnel = (step: string, properties?: Record<string, any>) => {
  mixpanelTracker.trackSubscriptionFunnel(step, properties);
};

Usage Example

// Identify user on login
identify('user_12345');

// Set user profile
setUserProfile({
  $name: 'Jane Doe',
  $email: 'jane@fitness-studio.com',
  subscription_tier: 'professional',
  industry: 'fitness',
  first_app_created: '2026-12-15',
});

// Track conversation funnel
trackConversationFunnel('started', {
  app_id: 'fitness-booking-app',
  source: 'chatgpt_store',
});

trackConversationFunnel('message_sent', {
  message_length: 42,
  conversation_turn: 1,
});

trackConversationFunnel('tool_invoked', {
  tool_name: 'create_booking',
  execution_time_ms: 320,
});

// Track subscription funnel
trackSubscriptionFunnel('pricing_viewed', {
  source: 'dashboard',
  current_tier: 'free',
});

trackSubscriptionFunnel('plan_selected', {
  selected_tier: 'professional',
  billing_cycle: 'monthly',
});

// Increment usage counter
mixpanelTracker.incrementProperty('total_messages_sent');
mixpanelTracker.incrementProperty('total_tools_invoked');

// Track revenue
mixpanelTracker.trackRevenue(149, {
  tier: 'professional',
  billing_cycle: 'monthly',
  payment_method: 'stripe',
});

Amplitude Setup: Product Intelligence at Scale

Amplitude is the gold standard for product analytics, offering advanced cohort analysis, predictive analytics, and behavioral cohorting. It's ideal for ChatGPT apps with complex user journeys and multiple conversion paths.

Why Amplitude for ChatGPT Apps?

Behavioral cohorting: Group users by actions (e.g., "users who invoked 3+ tools")
Predictive analytics: Identify users likely to churn or upgrade
Path analysis: Visualize common user journeys
Experimentation platform: Built-in A/B testing framework
Data warehouse sync: Export to Snowflake, BigQuery, Redshift

Production-Ready Amplitude SDK Setup

// lib/analytics/amplitude-tracker.ts
/**
 * Production-ready Amplitude integration for ChatGPT apps
 *
 * Features:
 * - Event taxonomy enforcement
 * - User property management
 * - Group analytics (for B2B)
 * - Revenue tracking
 * - Experiment tracking
 */

import * as amplitude from '@amplitude/analytics-browser';
import { Types } from '@amplitude/analytics-browser';

interface AmplitudeConfig {
  apiKey: string;
  debug?: boolean;
  serverZone?: 'US' | 'EU';
}

class AmplitudeTracker {
  private config: AmplitudeConfig;
  private initialized: boolean = false;

  constructor(config: AmplitudeConfig) {
    this.config = config;
    this.initialize();
  }

  /**
   * Initialize Amplitude
   */
  private async initialize(): Promise<void> {
    await amplitude.init(this.config.apiKey, undefined, {
      logLevel: this.config.debug ? Types.LogLevel.Debug : Types.LogLevel.Error,
      serverZone: this.config.serverZone || 'US',
      defaultTracking: {
        sessions: true,
        pageViews: false, // ChatGPT apps don't have traditional pageviews
        formInteractions: true,
        fileDownloads: true,
      },
    });

    this.initialized = true;

    if (this.config.debug) {
      console.log('[Amplitude] Initialized');
    }
  }

  /**
   * Track event with taxonomy enforcement
   */
  async trackEvent(
    eventName: string,
    eventProperties?: Record<string, any>
  ): Promise<void> {
    if (!this.initialized) {
      console.error('[Amplitude] Not initialized');
      return;
    }

    // Enforce event naming convention
    const normalizedEventName = this.normalizeEventName(eventName);

    const result = await amplitude.track(normalizedEventName, {
      ...eventProperties,
      platform: 'chatgpt',
      timestamp: Date.now(),
    });

    if (this.config.debug) {
      console.log('[Amplitude] Event tracked:', normalizedEventName, eventProperties);
    }
  }

  /**
   * Identify user
   */
  identify(userId: string, userProperties?: Record<string, any>): void {
    amplitude.setUserId(userId);

    if (userProperties) {
      const identifyEvent = new amplitude.Identify();

      for (const [key, value] of Object.entries(userProperties)) {
        identifyEvent.set(key, value);
      }

      amplitude.identify(identifyEvent);
    }

    if (this.config.debug) {
      console.log('[Amplitude] User identified:', userId, userProperties);
    }
  }

  /**
   * Set user properties
   */
  setUserProperties(properties: Record<string, any>): void {
    const identifyEvent = new amplitude.Identify();

    for (const [key, value] of Object.entries(properties)) {
      identifyEvent.set(key, value);
    }

    amplitude.identify(identifyEvent);

    if (this.config.debug) {
      console.log('[Amplitude] User properties set:', properties);
    }
  }

  /**
   * Set user properties once (only if not already set)
   */
  setUserPropertiesOnce(properties: Record<string, any>): void {
    const identifyEvent = new amplitude.Identify();

    for (const [key, value] of Object.entries(properties)) {
      identifyEvent.setOnce(key, value);
    }

    amplitude.identify(identifyEvent);
  }

  /**
   * Increment user property
   */
  incrementUserProperty(property: string, value: number = 1): void {
    const identifyEvent = new amplitude.Identify();
    identifyEvent.add(property, value);
    amplitude.identify(identifyEvent);

    if (this.config.debug) {
      console.log(`[Amplitude] Incremented ${property} by ${value}`);
    }
  }

  /**
   * Append to user property array
   */
  appendUserProperty(property: string, value: any): void {
    const identifyEvent = new amplitude.Identify();
    identifyEvent.append(property, value);
    amplitude.identify(identifyEvent);
  }

  /**
   * Set group (for B2B analytics)
   */
  setGroup(groupType: string, groupName: string | string[]): void {
    amplitude.setGroup(groupType, groupName);

    if (this.config.debug) {
      console.log('[Amplitude] Group set:', groupType, groupName);
    }
  }

  /**
   * Track revenue
   */
  async trackRevenue(amount: number, properties?: Record<string, any>): Promise<void> {
    const revenueEvent = new amplitude.Revenue();
    revenueEvent.setPrice(amount);

    if (properties) {
      for (const [key, value] of Object.entries(properties)) {
        revenueEvent.setEventProperties({ [key]: value });
      }
    }

    await amplitude.revenue(revenueEvent);

    if (this.config.debug) {
      console.log('[Amplitude] Revenue tracked:', amount, properties);
    }
  }

  /**
   * Reset user (on logout)
   */
  reset(): void {
    amplitude.reset();

    if (this.config.debug) {
      console.log('[Amplitude] User reset');
    }
  }

  /**
   * Normalize event name to follow taxonomy
   */
  private normalizeEventName(eventName: string): string {
    // Enforce naming convention: Object + Action
    // Examples: "Message Sent", "Tool Invoked", "Widget Rendered"
    const words = eventName.split(/[\s_-]+/);
    return words
      .map(word => word.charAt(0).toUpperCase() + word.slice(1).toLowerCase())
      .join(' ');
  }
}

// Export singleton instance
export const amplitudeTracker = new AmplitudeTracker({
  apiKey: process.env.AMPLITUDE_API_KEY!,
  debug: process.env.NODE_ENV === 'development',
  serverZone: 'US',
});

// Convenience methods
export const trackEvent = async (
  eventName: string,
  eventProperties?: Record<string, any>
) => {
  await amplitudeTracker.trackEvent(eventName, eventProperties);
};

export const identify = (userId: string, userProperties?: Record<string, any>) => {
  amplitudeTracker.identify(userId, userProperties);
};

export const setUserProperties = (properties: Record<string, any>) => {
  amplitudeTracker.setUserProperties(properties);
};

export const incrementUserProperty = (property: string, value?: number) => {
  amplitudeTracker.incrementUserProperty(property, value);
};

Usage Example

// Identify user
identify('user_12345', {
  subscription_tier: 'professional',
  industry: 'fitness',
  total_apps: 5,
});

// Track events
await trackEvent('Message Sent', {
  message_length: 42,
  tool_invoked: false,
  conversation_turn: 3,
});

await trackEvent('Tool Invoked', {
  tool_name: 'create_booking',
  execution_time_ms: 320,
  success: true,
});

// Increment counters
incrementUserProperty('total_messages_sent');
incrementUserProperty('total_tools_invoked');

// Track revenue
await amplitudeTracker.trackRevenue(149, {
  tier: 'professional',
  billing_cycle: 'monthly',
  payment_method: 'stripe',
});

// Set group (for B2B)
amplitudeTracker.setGroup('company', 'Fitness Studio Inc');

Conversion Tracking: Measuring What Matters

Conversion tracking connects analytics events to business outcomes: trial signups, paid subscriptions, feature activations, and revenue milestones.

Production-Ready Conversion Tracker

// lib/analytics/conversion-tracker.ts
/**
 * Multi-platform conversion tracker
 *
 * Tracks conversions across GA4, Mixpanel, and Amplitude
 */

import { ga4 } from './ga4-tracker';
import { mixpanelTracker } from './mixpanel-tracker';
import { amplitudeTracker } from './amplitude-tracker';

interface ConversionEvent {
  name: string;
  value?: number;
  currency?: string;
  properties?: Record<string, any>;
}

class ConversionTracker {
  /**
   * Track trial signup
   */
  async trackTrialSignup(properties?: Record<string, any>): Promise<void> {
    const event: ConversionEvent = {
      name: 'trial_signup',
      value: 0,
      currency: 'USD',
      properties: {
        ...properties,
        conversion_type: 'trial_signup',
      },
    };

    await this.trackConversion(event);
  }

  /**
   * Track subscription
   */
  async trackSubscription(
    tier: string,
    amount: number,
    properties?: Record<string, any>
  ): Promise<void> {
    const event: ConversionEvent = {
      name: 'subscription_completed',
      value: amount,
      currency: 'USD',
      properties: {
        ...properties,
        tier,
        conversion_type: 'subscription',
      },
    };

    await this.trackConversion(event);

    // Track revenue
    mixpanelTracker.trackRevenue(amount, { tier, ...properties });
    await amplitudeTracker.trackRevenue(amount, { tier, ...properties });
  }

  /**
   * Track app creation (feature activation)
   */
  async trackAppCreation(properties?: Record<string, any>): Promise<void> {
    const event: ConversionEvent = {
      name: 'app_created',
      properties: {
        ...properties,
        conversion_type: 'feature_activation',
      },
    };

    await this.trackConversion(event);
  }

  /**
   * Track app deployment
   */
  async trackAppDeployment(properties?: Record<string, any>): Promise<void> {
    const event: ConversionEvent = {
      name: 'app_deployed',
      properties: {
        ...properties,
        conversion_type: 'feature_activation',
      },
    };

    await this.trackConversion(event);
  }

  /**
   * Track custom conversion
   */
  async trackConversion(event: ConversionEvent): Promise<void> {
    // GA4
    await ga4.trackEvent(event.name, {
      value: event.value,
      currency: event.currency,
      ...event.properties,
    });

    // Mixpanel
    mixpanelTracker.trackEvent(event.name, {
      value: event.value,
      currency: event.currency,
      ...event.properties,
    });

    // Amplitude
    await amplitudeTracker.trackEvent(event.name, {
      value: event.value,
      currency: event.currency,
      ...event.properties,
    });

    console.log('[Conversion] Tracked:', event.name, event.properties);
  }
}

// Export singleton instance
export const conversionTracker = new ConversionTracker();

// Convenience methods
export const trackTrialSignup = (properties?: Record<string, any>) => {
  return conversionTracker.trackTrialSignup(properties);
};

export const trackSubscription = (
  tier: string,
  amount: number,
  properties?: Record<string, any>
) => {
  return conversionTracker.trackSubscription(tier, amount, properties);
};

export const trackAppCreation = (properties?: Record<string, any>) => {
  return conversionTracker.trackAppCreation(properties);
};

export const trackAppDeployment = (properties?: Record<string, any>) => {
  return conversionTracker.trackAppDeployment(properties);
};

Usage Example

// Track trial signup
await trackTrialSignup({
  source: 'pricing_page',
  plan: 'professional',
});

// Track subscription
await trackSubscription('professional', 149, {
  billing_cycle: 'monthly',
  payment_method: 'stripe',
  promo_code: 'LAUNCH50',
});

// Track app creation
await trackAppCreation({
  app_type: 'fitness_booking',
  creation_method: 'instant_wizard',
  template_used: 'mindbody_integration',
});

// Track app deployment
await trackAppDeployment({
  app_id: 'fitness-booking-app',
  deployment_target: 'chatgpt_store',
  deployment_time_seconds: 45,
});

Event Testing: Validation and Debugging

Before deploying analytics to production, validate that events are being sent correctly and parameters are accurate.

Production-Ready Event Validator

// lib/analytics/event-validator.ts
/**
 * Analytics event validator
 *
 * Validates events against schema before sending
 */

interface EventSchema {
  name: string;
  requiredParams: string[];
  optionalParams?: string[];
  paramTypes?: Record<string, string>;
}

class EventValidator {
  private schemas: Map<string, EventSchema> = new Map();

  constructor() {
    this.defineSchemas();
  }

  /**
   * Define event schemas
   */
  private defineSchemas(): void {
    this.schemas.set('chatgpt_message_sent', {
      name: 'chatgpt_message_sent',
      requiredParams: ['message_length', 'conversation_turn'],
      optionalParams: ['tool_invoked', 'widget_rendered'],
      paramTypes: {
        message_length: 'number',
        conversation_turn: 'number',
        tool_invoked: 'boolean',
        widget_rendered: 'boolean',
      },
    });

    this.schemas.set('chatgpt_tool_invoked', {
      name: 'chatgpt_tool_invoked',
      requiredParams: ['tool_name', 'execution_time_ms'],
      optionalParams: ['success', 'error_message'],
      paramTypes: {
        tool_name: 'string',
        execution_time_ms: 'number',
        success: 'boolean',
        error_message: 'string',
      },
    });

    this.schemas.set('subscription_completed', {
      name: 'subscription_completed',
      requiredParams: ['tier', 'amount', 'currency'],
      optionalParams: ['billing_cycle', 'payment_method', 'promo_code'],
      paramTypes: {
        tier: 'string',
        amount: 'number',
        currency: 'string',
        billing_cycle: 'string',
        payment_method: 'string',
        promo_code: 'string',
      },
    });
  }

  /**
   * Validate event
   */
  validate(eventName: string, params: Record<string, any>): {
    valid: boolean;
    errors: string[];
  } {
    const schema = this.schemas.get(eventName);

    if (!schema) {
      return {
        valid: false,
        errors: [`Event schema not found: ${eventName}`],
      };
    }

    const errors: string[] = [];

    // Check required parameters
    for (const requiredParam of schema.requiredParams) {
      if (!(requiredParam in params)) {
        errors.push(`Missing required parameter: ${requiredParam}`);
      }
    }

    // Check parameter types
    if (schema.paramTypes) {
      for (const [param, expectedType] of Object.entries(schema.paramTypes)) {
        if (param in params) {
          const actualType = typeof params[param];
          if (actualType !== expectedType) {
            errors.push(
              `Invalid type for ${param}: expected ${expectedType}, got ${actualType}`
            );
          }
        }
      }
    }

    return {
      valid: errors.length === 0,
      errors,
    };
  }
}

// Export singleton instance
export const eventValidator = new EventValidator();

// Validate event helper
export const validateEvent = (eventName: string, params: Record<string, any>) => {
  return eventValidator.validate(eventName, params);
};

Multi-Platform Analytics Debugger

// lib/analytics/analytics-debugger.ts
/**
 * Analytics debugger
 *
 * Logs all analytics events to console in development mode
 */

import { ga4 } from './ga4-tracker';
import { mixpanelTracker } from './mixpanel-tracker';
import { amplitudeTracker } from './amplitude-tracker';
import { eventValidator } from './event-validator';

class AnalyticsDebugger {
  private enabled: boolean;

  constructor() {
    this.enabled = process.env.NODE_ENV === 'development';
  }

  /**
   * Track event with validation and debugging
   */
  async trackEvent(
    eventName: string,
    params?: Record<string, any>
  ): Promise<void> {
    // Validate event
    const validation = eventValidator.validate(eventName, params || {});

    if (!validation.valid) {
      console.error('[Analytics] Event validation failed:', validation.errors);

      if (this.enabled) {
        // Show validation errors in development
        alert(`Analytics validation failed:\n${validation.errors.join('\n')}`);
      }

      return;
    }

    // Log event
    if (this.enabled) {
      console.group(`[Analytics] ${eventName}`);
      console.log('Parameters:', params);
      console.log('Timestamp:', new Date().toISOString());
      console.groupEnd();
    }

    // Track across all platforms
    await Promise.all([
      ga4.trackEvent(eventName, params),
      mixpanelTracker.trackEvent(eventName, params),
      amplitudeTracker.trackEvent(eventName, params),
    ]);
  }

  /**
   * Enable/disable debugging
   */
  setEnabled(enabled: boolean): void {
    this.enabled = enabled;
    console.log(`[Analytics] Debugging ${enabled ? 'enabled' : 'disabled'}`);
  }
}

// Export singleton instance
export const analyticsDebugger = new AnalyticsDebugger();

// Convenience method
export const trackEvent = (eventName: string, params?: Record<string, any>) => {
  return analyticsDebugger.trackEvent(eventName, params);
};

Conclusion: Analytics-Driven ChatGPT App Success

Custom event tracking is the foundation of data-driven product development. By implementing GA4, Mixpanel, and Amplitude with production-ready code, you gain:

Visibility: See exactly how users interact with your ChatGPT app
Optimization: Identify conversion bottlenecks and fix them
Growth: Double down on features that drive engagement and revenue
Retention: Detect early churn signals and intervene proactively

Key Takeaways

GA4: Best for high-level funnels, acquisition tracking, and free tier (10M events/month)
Mixpanel: Best for user-centric analytics, cohort analysis, and funnel visualization
Amplitude: Best for behavioral cohorting, predictive analytics, and advanced segmentation
Multi-platform tracking: Send events to all three platforms for comprehensive coverage
Event validation: Enforce schemas to prevent bad data from corrupting dashboards
Conversion tracking: Connect analytics to revenue outcomes (trials, subscriptions, LTV)

Next Steps

Implement event tracking: Copy the production-ready code examples into your ChatGPT app
Define event taxonomy: Document all events, parameters, and user properties
Set up dashboards: Create real-time dashboards in GA4, Mixpanel, and Amplitude
Monitor conversions: Track trial signups, subscriptions, and feature activations
Optimize funnels: Identify drop-off points and A/B test improvements

Ready to Build Your ChatGPT App?

MakeAIHQ.com provides built-in analytics tracking for all ChatGPT apps created with our no-code platform. Get started with our 5-step Instant App Wizard and deploy to the ChatGPT App Store in 48 hours—no coding required.

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External Resources

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MakeAIHQ.com is the leading no-code platform for building ChatGPT applications. From zero to ChatGPT App Store in 48 hours—no coding required. Trusted by 1,000+ businesses in fitness, restaurants, real estate, and professional services.

Keywords: custom event tracking chatgpt, ga4 events, mixpanel integration, amplitude tracking, user properties, event parameters, conversion tracking, funnel optimization, analytics implementation, chatgpt app analytics

Custom Event Tracking: GA4, Mixpanel & Amplitude Integration

Introduction: Why Custom Events Are Critical for ChatGPT Apps

GA4 Event Tracking: The Foundation

Why GA4 for ChatGPT Apps?

GA4 Event Structure

Production-Ready GA4 Event Tracker

Usage Example

Mixpanel Integration: Deep User Insights

Why Mixpanel for ChatGPT Apps?

Production-Ready Mixpanel Integration

Usage Example

Amplitude Setup: Product Intelligence at Scale

Why Amplitude for ChatGPT Apps?

Production-Ready Amplitude SDK Setup

Usage Example

Conversion Tracking: Measuring What Matters

Production-Ready Conversion Tracker

Usage Example

Event Testing: Validation and Debugging

Production-Ready Event Validator

Multi-Platform Analytics Debugger

Conclusion: Analytics-Driven ChatGPT App Success

Key Takeaways

Next Steps

Ready to Build Your ChatGPT App?

Internal Resources

External Resources

MakeAIHQ Team

Ready to Build Your ChatGPT App?