const posthog = new PostHog(process.env.NEXT_PUBLIC_POSTHOG_KEY!, { host: 'https://us.i.posthog.com', });

async function main() { // 1. Capture a custom event posthog.capture({ distinctId: 'user-123', event: 'hello_posthog', properties: { greeting: 'Hello from posthog-node!', source: 'hello-world-skill', timestamp: new Date().toISOString(), }, }); console.log('Event captured: hello_posthog');

// 2. Identify a user with properties posthog.identify({ distinctId: 'user-123', properties: { email: 'dev@example.com', name: 'Dev User', plan: 'free', }, }); console.log('User identified: user-123');

// 3. Check a feature flag const flagValue = await posthog.getFeatureFlag('my-feature-flag', 'user-123'); console.log(Feature flag "my-feature-flag": ${flagValue});

// 4. Flush and shutdown (required in scripts/serverless) await posthog.shutdown(); console.log('Done — check app.posthog.com Activity tab'); }

main().catch(console.error);


### Step 2: Browser Hello World (posthog-js)

```typescript
// In a React component or vanilla JS
import posthog from 'posthog-js';

// Initialize (call once at app startup)
posthog.init('phc_your_project_key', {
  api_host: 'https://us.i.posthog.com',
  loaded: () => console.log('PostHog loaded'),
});

// Capture a custom event
posthog.capture('button_clicked', {
  button_name: 'signup',
  page: window.location.pathname,
});

// Identify the user after login
posthog.identify('user-123', {
  email: 'user@example.com',
  plan: 'pro',
});

// Check a feature flag
if (posthog.isFeatureEnabled('new-checkout')) {
  console.log('New checkout flow is enabled');
}

// Associate user with a company (group analytics)
posthog.group('company', 'company-456', {
  name: 'Acme Corp',
  plan: 'enterprise',
});

Step 3: Python Hello World

import posthog

posthog.project_api_key = 'phc_your_project_key'
posthog.host = 'https://us.i.posthog.com'

# Capture event
posthog.capture('user-123', 'hello_posthog', {
    'greeting': 'Hello from Python!',
})

# Identify user
posthog.identify('user-123', {
    'email': 'dev@example.com',
    'plan': 'free',
})

# Feature flag
is_enabled = posthog.feature_enabled('my-flag', 'user-123')
print(f'Flag enabled: {is_enabled}')

Step 4: Raw HTTP API (No SDK)

set -euo pipefail
# Capture event via POST to /capture/
curl -X POST 'https://us.i.posthog.com/capture/' \
  -H 'Content-Type: application/json' \
  -d '{
    "api_key": "phc_your_project_key",
    "event": "hello_posthog",
    "distinct_id": "user-123",
    "properties": {
      "greeting": "Hello from curl!"
    }
  }'

# Batch capture multiple events
curl -X POST 'https://us.i.posthog.com/batch/' \
  -H 'Content-Type: application/json' \
  -d '{
    "api_key": "phc_your_project_key",
    "batch": [
      {"event": "page_viewed", "distinct_id": "user-123", "properties": {"page": "/home"}},
      {"event": "button_clicked", "distinct_id": "user-123", "properties": {"button": "cta"}}
    ]
  }'

Error Handling

Error	Cause	Solution
Events not in dashboard	Not flushed	Call `await posthog.shutdown()` or `posthog.flush()`
`posthog.init` silently fails	Wrong API host	Use `us.i.posthog.com` (not `app.posthog.com`)
Feature flag returns `undefined`	Flag not created yet	Create flag in PostHog dashboard first
`identify` not linking	Different `distinct_id`	Frontend and backend must use the same `distinct_id`
Python events missing	No flush before exit	`posthog.shutdown()` or `posthog.flush()` at end

Output

Working event capture in PostHog Activity tab
User identified with properties in Persons view
Feature flag evaluation result logged
Console output confirming each operation

Resources

Next Steps

Proceed to posthog-local-dev-loop for development workflow setup.

posthog-hello-world

PostHog Hello World

Overview

Prerequisites

Instructions

Step 1: Capture Your First Event (Node.js)