PostHog¶

What it is¶

An all-in-one product OS that includes product analytics, session replay, feature flags, and A/B testing.

What problem it solves¶

It helps teams understand how users interact with their applications and allows for data-driven product decisions.

Where it fits in the stack¶

Category: Process & Understanding / Product Analytics

LLM Features¶

LLM Observability: Track agent behavior and user feedback alongside traditional product metrics like conversion and retention.
Trace Management: Capture and visualize LLM traces to debug agent decision-making.
OpenRouter Integration: Native support for receiving event logs from OpenRouter sessions to monitor model performance and costs.

Getting started¶

Installation¶

pip install posthog

Capturing LLM Events¶

import posthog

posthog.project_api_key = '<ph_project_api_key>'
posthog.host = 'https://us.i.posthog.com'

posthog.capture('user_id', 'llm_interaction', {
    'model': 'gpt-4o',
    'prompt_tokens': 150,
    'completion_tokens': 200,
    'total_cost': 0.005,
    'user_feedback': 'helpful'
})

CLI examples¶

Authenticates the CLI with your PostHog instance:

posthog-cli login

posthog-cli query¶

Executes a HogQL (SQL) query against your PostHog data directly from the terminal:

posthog-cli query "SELECT event, count() FROM events GROUP BY event"

posthog-cli capture¶

Sends a manual event to PostHog for testing purposes:

posthog-cli capture --distinct-id user_123 --event test_event --properties '{"source": "cli"}'

API examples¶

Python (AI Trace Instrumentation)¶

PostHog can be integrated into AI pipelines to track multi-step agent actions using their SDK's properties to link traces to specific user sessions.

import posthog

# Link an AI trace to a user session
posthog.capture('user_123', 'ai_trace_step', {
    'trace_id': 'uuid-1234',
    'step_name': 'retrieval',
    'context_found': True
})

Python (Feature Flag Evaluation)¶

import posthog

posthog.project_api_key = '<ph_project_api_key>'

# Check if a new AI model feature flag is enabled for a user
if posthog.feature_enabled('use-new-llm-model', 'user_123'):
    # Logic for new model
    pass
else:
    # Logic for fallback model
    pass

Sources / references¶

Contribution Metadata¶

Last reviewed: 2026-04-26
Confidence: high