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Integration Flask

PostHogOfficialCreated by PostHog

  • Skill
  • Tool integration
  • Data and AI
  • MIT
  • Low risk
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From the author

PostHog integration for Flask applications
— the description by PostHog

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a systematic workflow for developers to integrate PostHog into Flask web applications. It covers the setup of the PostHog Python SDK, best practices for event tracking, user identification, and error monitoring. The skill emphasizes secure configuration using environment variables and provides patterns for tracking critical business operations, such as authentication and API interactions, while strictly avoiding the transmission of PII in event properties.

What it does

  • Provides a step-by-step workflow for PostHog integration
  • Defines patterns for user identification and property tracking
  • Outlines methods for manual exception capture and error tracking
  • Demonstrates feature flag implementation with payload support
  • Establishes security guidelines for handling PII and environment variables
  • Includes reference examples for Flask-based project structures

When to use it

  • When adding analytics to a new or existing Flask application
  • When implementing user behavior tracking and conversion funnels
  • When setting up error monitoring for critical API endpoints
  • When integrating feature flags to manage application functionality

Advantages

  • Ensures consistent implementation across the application
  • Promotes secure handling of sensitive user data
  • Provides clear separation between event properties and user identification
  • Standardizes error tracking practices for better observability

Usage examples

“How do I initialize PostHog in my Flask application?”
The skill guides you to initialize the PostHog client globally within the create_app() factory function using the Posthog() constructor, ensuring proper configuration and exception autocapture.
“Where should I track user signup events?”
The skill instructs you to identify the user and capture the signup event during the registration flow, using identify_context() for user properties and capture() for the event.

Install

  1. Download the skill as a ZIP:

    https://autogineer.com/agent-skills/posthog/integration-flask/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip integration-flask.zip -d .agents/skills

Documentation by PostHog

PostHog integration for Flask

This skill helps you add PostHog analytics to Flask applications.

Workflow

Follow these steps in order to complete the integration:

  1. basic-integration-1.0-begin.md - PostHog Setup - Begin ← Start here

  2. basic-integration-1.1-edit.md - PostHog Setup - Edit

  3. basic-integration-1.2-revise.md - PostHog Setup - Revise

  4. basic-integration-1.3-conclude.md - PostHog Setup - Conclusion

Reference files

  • references/EXAMPLE.md - Flask example project code

  • references/flask.md - Flask - docs

  • references/identify-users.md - Identify users - docs

  • references/basic-integration-1.0-begin.md - PostHog setup - begin

  • references/basic-integration-1.1-edit.md - PostHog setup - edit

  • references/basic-integration-1.2-revise.md - PostHog setup - revise

  • references/basic-integration-1.3-conclude.md - PostHog setup - conclusion

The example project shows the target implementation pattern. Consult the documentation for API details.

Key principles

  • Environment variables: Always use environment variables for PostHog keys. Never hardcode them.

  • Minimal changes: Add PostHog code alongside existing integrations. Don't replace or restructure existing code.

  • Match the example: Your implementation should follow the example project's patterns as closely as possible.

Framework guidelines

  • Initialize PostHog globally in create_app() using posthog.api_key and posthog.host (NOT per-request)

  • Manually capture exceptions with posthog.capture_exception(e) for error tracking since Flask has built-in error handlers

  • Blueprint registration happens AFTER PostHog initialization in create_app()

  • Remember that source code is available in the venv/site-packages directory

  • posthog is the Python SDK package name

  • Install dependencies with pip install posthog or pip install -r requirements.txt and do NOT use unquoted version specifiers like >= directly in shell commands

  • In CLIs and scripts: MUST call posthog.shutdown() before exit or all events are lost

  • Always use the Posthog() class constructor (instance-based API) instead of module-level posthog.api_key config

  • Always include enable_exception_autocapture=True in the Posthog() constructor to automatically track exceptions

  • NEVER send PII in capture() event properties — no emails, full names, phone numbers, physical addresses, IP addresses, or user-generated content

  • PII belongs in identify() person properties, NOT in capture() event properties. Safe event properties are metadata like message_length, form_type, boolean flags.

  • Register posthog_client.shutdown with atexit.register() to ensure all events are flushed on exit

  • The Python SDK has NO identify() method — use posthog_client.set(distinct_id=user_id, properties={...}) to set person properties, or use identify_context(user_id) within a context

Identifying users

Identify users during login and signup events. Refer to the example code and documentation for the correct identify pattern for this framework. If both frontend and backend code exist, pass the client-side session and distinct ID using X-POSTHOG-DISTINCT-ID and X-POSTHOG-SESSION-ID headers to maintain correlation.

Error tracking

Add PostHog error tracking to relevant files, particularly around critical user flows and API boundaries.

Files

references/flask.md

Flask - Docs

PostHog makes it easy to get data about traffic and usage of your Flask app. Integrating PostHog enables analytics, custom events capture, feature flags, and more.

This guide walks you through integrating PostHog into your Flask app using the Python SDK.

Installation

To start, run pip install posthog to install PostHog’s Python SDK.

Then, initialize PostHog where you'd like to use it. For example, here's how to capture an event in a simple route:

app.py

PostHog AI

package main
from flask import Flask, render_template, request, redirect, session, url_for
from posthog import Posthog
posthog = Posthog(
  '<ph_project_token>',
  host='https://us.i.posthog.com'
)
@app.route('/api/dashboard', methods=['POST'])
def api_dashboard():
    posthog.capture(
        'dashboard_api_called'
        distinct_id='distinct_id_of_your_user',
    )
    return '', 204

You can find your project token and instance address in your project settings.

Identifying users

Identifying users is required. Backend events need a distinct_id that matches the ID your frontend uses when calling posthog.identify(). Without this, backend events are orphaned — they can't be linked to frontend event captures, session replays, LLM traces, or error tracking.

See our guide on identifying users for how to set this up.

Error tracking

Flask has built-in error handlers. This means PostHog’s default exception autocapture won’t work and we need to manually capture errors instead using capture_exception():

Python

PostHog AI

from flask import Flask, jsonify
from posthog import Posthog
posthog = Posthog('<ph_project_token>', host='https://us.i.posthog.com')
@app.errorhandler(Exception)
def handle_exception(e):
    # Capture methods, including capture_exception, return the UUID of the captured event,
    # which you can use to find specific errors users encountered
    event_id = posthog.capture_exception(e)
    # You can show the event ID to your user, and ask them to include it in bug reports
    response = jsonify({'message': str(e), 'error_id': event_id})
    response.status_code = 500
    return response

Next steps

For any technical questions for how to integrate specific PostHog features into Flask (such as analytics, feature flags, A/B testing, etc.), have a look at our Python SDK docs.

Alternatively, the following tutorials can help you get started:

Community questions

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Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs an API key, Needs Python

Security

What our scanner noticed· Low risk

  • Instructions that use the network

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Created by
PostHog
Publisher
PostHog (Official)
Source
PostHog/skills · skills/posthog/integration/skills/flask · commit a5d30e7
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
Synced
Also distributed in
PostHog/skills

AutoGineer is not affiliated with or endorsed by PostHog or PostHog.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download integration-flask.zip