PostHog Event Ingestion Cost Calculator

// lib/posthog.ts - Optimize PostHog ingestion bills by 60% with client-side filtering
import posthog from 'posthog-js';

posthog.init(process.env.NEXT_PUBLIC_POSTHOG_KEY!, {
  api_host: 'https://us.i.posthog.com',
  
  // Disable noisy auto-capture that logs every single generic scroll and keystroke
  autocapture: {
    capture_copied_text: false,
    css_selector_allowlist: ['[data-track]'] // Only capture buttons explicitly tagged with data-track
  },
  
  // Sample Session Replays to 10% of users to avoid massive recording overages
  session_recording: {
    sample_rate: 0.10,
    mask_all_element_attributes: true,
    mask_all_text: true
  }
});

PostHog Event Ingestion Economics: Free Tiers, Session Replay & Volume TCO

PostHog's pricing structure combines generous free developer allowances (1 million events and 5,000 session recordings free per month) with tiered metered usage. However, as web and mobile SaaS applications scale, high-frequency client-side events (such as `mousemove`, input change listeners, and automated bot scrapers) can trigger unexpected bill spikes. PostHog charges $0.00045/event for the first paid tier, dropping down to $0.00002/event at enterprise volumes.

Production Pipeline: Client-Side Sampling & Sensitive Field Redaction

Configuring PostHog initialization with client-side event debouncing and session replay sampling prevents runaway billing while maintaining GDPR compliance:

import posthog from 'posthog-js';

posthog.init('YOUR_PROJECT_API_KEY', {
  api_host: 'https://us.i.posthog.com',
  person_profiles: 'identified_only', // Avoid anonymous profile accumulation
  session_recording: {
    maskAllInputs: true,
    maskTextSelector: '.sensitive-data',
    sampleRate: 0.20, // Record only 20% of sessions to cut replay bills by 80%
  },
  capture_performance: false, // Drop high-frequency network timing logs
  autocapture: {
    dom_event_allowlist: ['click', 'submit'], // Exclude continuous scroll/mouse moves
  }
});

Production Governance & Ingestion Optimization

• Set Billing Limits in Dashboard: Configure strict hard billing limits in the PostHog project settings. Once the spend threshold is met, PostHog drops subsequent non-critical analytics events while keeping auth flows operational.
• Filter Internal Team Traffic: Exclude development domains (`localhost`, `staging.yourdomain.com`) and employee IP CIDR blocks to avoid polluting analytics datasets and burning monthly event quotas.
• Server-Side Event Batching: For high-volume backend microservices, use PostHog's Node.js or Python SDK with `flushAt: 50` and `flushInterval: 10000` to batch HTTP dispatches and minimize network socket overhead.

Frequently Asked PostHog Ingestion & Budgeting Questions

Q: How does PostHog calculate monthly event allowances across multiple projects?
A: The 1 million free event and 5,000 free session recording allowances apply per organization account per month, shared dynamically across all child projects and development environments.

Q: How does setting session recording sample rates reduce monthly bills?
A: Setting `sampleRate: 0.20` captures 20% of user sessions, providing statistically representative UX telemetry while reducing session recording storage bills by exactly 80%.