PostHog

PostHog is an open-source product analytics platform that helps you understand user behavior. With PostHog’s LLM analytics, you can track and analyze your AI application usage.

Step 1: Get your PostHog project API key

In PostHog, navigate to your project settings:

1. Log in to your PostHog account
2. Go to Project Settings
3. Copy your Project API Key (starts with phc_...)

Step 2: Enable Broadcast in OpenRouter

Go to Settings > Broadcast and toggle Enable Broadcast.

Step 3: Configure PostHog

Click the edit icon next to PostHog and enter:

• Api Key: Your PostHog project API key (starts with phc_...)
• Endpoint (optional): Default is https://us.i.posthog.com. For EU region, use https://eu.i.posthog.com

Step 4: Test and save

Click Test Connection to verify the setup. The configuration only saves if the test passes.

Step 5: Send a test trace

Make an API request through OpenRouter and view the LLM analytics in your PostHog dashboard.

Custom Metadata

PostHog receives LLM analytics events with custom metadata included as event properties. Use the trace field to attach additional context to your analytics data.

Supported Metadata Keys

Example

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{
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  "model": "openai/gpt-4o",
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  "messages": [{ "role": "user", "content": "Recommend a product..." }],
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  "user": "user_12345",
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  "session_id": "session_abc",
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  "trace": {
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    "trace_name": "Product Recommendations",
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    "generation_name": "Generate Recommendation",
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    "feature": "shopping-assistant",
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    "ab_test_group": "variant_b"
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  }
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}

Additional Context

• The user field maps to PostHog’s $ai_user property for user-level LLM analytics
• The session_id field maps to $ai_session_id for session grouping
• Custom metadata keys from trace are included as properties on the LLM analytics event
• PostHog’s LLM analytics dashboard automatically tracks token usage, costs, and model performance

Privacy Mode

When Privacy Mode is enabled for this destination, the $ai_input and $ai_output_choices properties are excluded from events. All other analytics data — token usage, costs, model information, and custom metadata — is still sent normally.