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Instrument Product Analytics

PostHogOfficialCreated by PostHog

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

Add PostHog product analytics events to track user behavior. Use after implementing new features or reviewing PRs to ensure meaningful user actions are captured. Also handles initial PostHog SDK setup if not yet installed.
— the description by PostHog

AutoGineer summary

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

This skill provides a structured, multi-step workflow to integrate PostHog product analytics into a wide variety of software projects. It guides the user through detecting the project's framework, installing the appropriate SDK, initializing the service, and strategically placing event capture calls. The skill emphasizes non-intrusive implementation, requiring that new analytics code be added alongside existing logic without altering the project's fundamental architecture. It also covers user identification, error tracking, and secure environment variable management.

What it does

  • Detects the project's framework and language to determine the correct PostHog SDK.
  • Handles initial SDK installation and initialization based on framework-specific patterns.
  • Identifies key user actions and business-critical events for tracking.
  • Implements event capture calls and user identification logic.
  • Configures environment variables securely for API tokens and host URLs.
  • Verifies the integration and performs targeted linting on modified files.

When to use it

  • After implementing new features that require tracking for product analytics.
  • When reviewing pull requests to ensure meaningful user behaviors are captured.
  • During the initial setup of a new project that needs product analytics.
  • When migrating or adding analytics to an existing application.

Advantages

  • Supports a broad range of frontend, backend, and mobile frameworks.
  • Ensures consistent event naming and property usage across the codebase.
  • Prioritizes non-breaking changes and minimal impact on existing code structure.
  • Automates the complex setup of environment variables and SDK initialization.

Usage examples

“Add PostHog analytics to my Next.js project.”
The agent will analyze the project structure, install the PostHog SDK, initialize it in the appropriate client/server files, and prompt you to identify key events to track.
“I need to track user signups and errors in my Django backend.”
The agent will locate your authentication logic, add identify calls, implement exception capture, and ensure the PostHog project tokens are managed via environment variables.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/posthog/instrument-product-analytics/download

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

    mkdir -p .agents/skills && unzip instrument-product-analytics.zip -d .agents/skills

Documentation by PostHog

Add PostHog product analytics events

Use this skill to add product analytics events (capture calls) that track meaningful user actions in new or changed code. Use it after implementing features or reviewing PRs to ensure key user behaviors are captured. If PostHog is not yet installed, this skill also covers initial SDK setup. Supports any framework or language.

Supported frameworks and languages: Next.js, React Router, Nuxt, Vue, TanStack Start, SvelteKit, Astro, Angular, Django, Flask, FastAPI, Laravel, PHP, Ruby on Rails, Go, Elixir, Android, iOS, Flutter, React Native, Expo, and more.

Instructions

Follow these steps IN ORDER:

STEP 1: Analyze the codebase and detect the platform.

Look for dependency files (package.json, pubspec.yaml, Podfile, Package.swift, requirements.txt, Gemfile, composer.json, go.mod, mix.exs, etc.) to determine the framework and language.

Look for lockfiles (pnpm-lock.yaml, package-lock.json, yarn.lock, bun.lockb, go.sum, pubspec.lock, Podfile.lock, Package.resolved, mix.lock) to determine the package manager.

  • Check for existing PostHog setup. If PostHog is already installed and initialized, skip to STEP 5.

STEP 2: Research integration. (Skip if PostHog is already set up.) 2.1. Find the reference file below that matches the detected framework — it is the source of truth for SDK initialization, provider setup, and event capture patterns. Read it now. 2.2. If no reference matches, fall back to your general knowledge and web search. Use posthog.com/docs as the primary search source.

STEP 3: Install the PostHog SDK. (Skip if PostHog is already set up.)

  • Add the PostHog SDK package for the detected platform. Do not manually edit package.json — use the package manager's install command.

STEP 4: Initialize PostHog. (Skip if PostHog is already set up.)

  • Follow the framework reference for where and how to initialize. This varies significantly by framework (e.g., instrumentation-client.ts for Next.js 15.3+, AppConfig.ready() for Django, create_app() for Flask).

STEP 5: Plan event tracking.

  • From the project's file list, select between 10 and 15 files that might have interesting business value for event tracking, especially conversion and churn events.

  • Also look for files related to login that could be used for identifying users, along with error handling.

  • Find any existing posthog.capture() code. Make note of event name formatting. Don't duplicate existing events; supplement them.

  • Track actions only, not pageviews (those can be captured automatically). Exceptions can be made for "viewed"-type events at the top of a conversion funnel.

  • Server-side events are REQUIRED if the project includes any instrumentable server-side code (API routes, server actions, webhook handlers, payment/checkout completion, authentication endpoints).

STEP 6: Implement event capture.

  • For each planned event, add posthog.capture() calls with useful properties.

  • If a file already has existing integration code for other tools or services, don't overwrite or remove that code. Place PostHog code below it.

  • Do not alter the fundamental architecture of existing files. Make additions minimal and targeted.

  • You must read a file immediately before attempting to write it.

STEP 7: Identify users.

  • Add PostHog identify() calls on the client side during login and signup events. Use the contents of login and signup forms to identify users on submit.

  • If both frontend and backend exist, pass the client-side session and distinct ID using X-POSTHOG-DISTINCT-ID and X-POSTHOG-SESSION-ID headers to the server-side code. On the server side, make sure events have a matching distinct ID.

STEP 8: Add error tracking.

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

STEP 9: Set up environment variables.

  • Check if the project already has PostHog environment variables configured (e.g. in .env, .env.local, or framework-specific env files). If valid values already exist, skip this step.

  • If the PostHog project token is missing, use the PostHog MCP server's projects-get tool to retrieve the project's api_token. If multiple projects are returned, ask the user which project to use. If the MCP server is not connected or not authenticated, ask the user for their PostHog project token instead.

  • For the PostHog host URL: check the projects-get MCP response for a region field — US maps to https://us.i.posthog.com, EU maps to https://eu.i.posthog.com. If the region is not available from the MCP response or from existing project configuration, ask the user: "Are you on PostHog US Cloud or EU Cloud?" Do not assume US Cloud.

  • Write these values to the appropriate env file using the framework's naming convention.

  • Reference these environment variables in code instead of hardcoding them.

STEP 10: Verify and clean up.

  • Check the project for errors. Look for type checking or build scripts in package.json.

  • Ensure any components created were actually used.

  • Run any linter or prettier-like scripts found in the package.json, but ONLY on the files you have edited or created during this session. Never run formatting or linting across the entire project's codebase.

Reference files

  • references/EXAMPLE-next-app-router.md - next-app-router example project code

  • references/EXAMPLE-next-pages-router.md - next-pages-router example project code

  • references/EXAMPLE-react-react-router-6.md - react-react-router-6 example project code

  • references/EXAMPLE-react-react-router-7-framework.md - react-react-router-7-framework example project code

  • references/EXAMPLE-react-react-router-7-data.md - react-react-router-7-data example project code

  • references/EXAMPLE-react-react-router-7-declarative.md - react-react-router-7-declarative example project code

  • references/EXAMPLE-nuxt-3-6.md - nuxt-3-6 example project code

  • references/EXAMPLE-nuxt-4.md - nuxt-4 example project code

  • references/EXAMPLE-vue-3.md - vue-3 example project code

  • references/EXAMPLE-react-tanstack-router-file-based.md - react-tanstack-router-file-based example project code

  • references/EXAMPLE-react-tanstack-router-code-based.md - react-tanstack-router-code-based example project code

  • references/EXAMPLE-tanstack-start.md - tanstack-start example project code

  • references/EXAMPLE-sveltekit.md - sveltekit example project code

  • references/EXAMPLE-astro-static.md - astro-static example project code

  • references/EXAMPLE-astro-view-transitions.md - astro-view-transitions example project code

  • references/EXAMPLE-astro-ssr.md - astro-ssr example project code

  • references/EXAMPLE-astro-hybrid.md - astro-hybrid example project code

  • references/EXAMPLE-angular.md - angular example project code

  • references/EXAMPLE-django.md - django example project code

  • references/EXAMPLE-flask.md - flask example project code

  • references/EXAMPLE-fastapi.md - fastapi example project code

  • references/EXAMPLE-python.md - python example project code

  • references/EXAMPLE-laravel.md - laravel example project code

  • references/EXAMPLE-php.md - php example project code

  • references/EXAMPLE-ruby-on-rails.md - ruby-on-rails example project code

  • references/EXAMPLE-ruby.md - ruby example project code

  • references/EXAMPLE-android.md - android example project code

  • references/EXAMPLE-swift.md - swift example project code

  • references/EXAMPLE-react-native.md - react-native example project code

  • references/EXAMPLE-expo.md - expo example project code

  • references/next-js.md - Next.js

  • references/react-router-v6.md - React router v6

  • references/react-router-v7-framework-mode.md - React router v7 framework mode (remix v3)

  • references/react-router-v7-data-mode.md - React router v7 data mode

  • references/react-router-v7-declarative-mode.md - React router v7 declarative mode

  • references/nuxt-js-3-6.md - Nuxt.js (v3.0 to v3.6)

  • references/nuxt-js.md - Nuxt.js

  • references/vue-js.md - Vue.js

  • references/tanstack-start.md - Tanstack start

  • references/svelte.md - Svelte

  • references/astro.md - Astro

  • references/angular.md - Angular

  • references/django.md - Django

  • references/flask.md - Flask

  • references/python.md - Python

  • references/posthog-python.md - PostHog python SDK

  • references/dotnet.md - .net

  • references/elixir.md - Elixir

  • references/go.md - Go

  • references/laravel.md - Laravel

  • references/php.md - Php

  • references/ruby-on-rails.md - Ruby on rails

  • references/ruby.md - Ruby

  • references/android.md - Android

  • references/ios.md - Ios

  • references/usage.md - Ios SDK usage

  • references/configuration.md - Ios SDK configuration

  • references/flutter.md - Flutter

  • references/react-native.md - React native

  • references/identify-users.md - Identify users

  • references/COMMANDMENTS.md - Framework-specific rules the integration must follow

Each framework reference contains SDK-specific installation, initialization, and usage patterns. Find the one matching the user's stack.

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 docs: Follow the framework reference's initialization and capture patterns exactly.

Files

references/flask.md

AI agents: this is one page from PostHog's docs. Full index of Markdown docs for LLMs: https://posthog.com/llms.txt

Flask

Canonical URL: https://posthog.com/docs/libraries/flask

Cloud region: This page uses US Cloud hosts. For an EU Cloud project, use https://eu.i.posthog.com instead of https://us.i.posthog.com (ingestion host), and use https://eu.posthog.com instead of https://app.posthog.com (app host for links).

On this page

  • Install with the wizard

  • Installation

  • Identifying users

  • Request contexts

  • Error tracking

  • Next steps

  • Supported versions

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

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

These docs cover version 7.x of the Python SDK, which requires Python 3.10 or higher. On Python 3.9? See supported versions.

Install with the wizard

Run this command in your project directory to add PostHog to your Flask project. The wizard detects your framework, installs the SDK, and sets up your first events.

npx @posthog/wizard

Or set it up manually by following the rest of this guide.

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

from flask import Flask
from posthog import Posthog

app = Flask(__name__)

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 to associate events with the correct user.

In Python, you can do this through a context. All event captures in the same context will be tagged automatically with the correct distinct_id. Typically, you would set a fresh context and identify at the top of each route.

from posthog import new_context, identify_context, capture

@app.get("/foo")
def foo(current_user: User = Depends(get_current_user)):
    with new_context(): # Set context at the top of a route
        identify_context(current_user.id)
        capture("foo_viewed")
    return {"status": "ok"}

When possible, write a small piece of middleware that resolves your authenticated user, wrap a context around the request, and identifies it. Every capture() downstream is then attributed automatically. The SDK's Django middleware does this automatically and you can replicate it when using the plain Python SDK.

Request contexts

Version 7.69.0 and later of the Python SDK includes a Flask integration that creates a fresh context for every request. It adds the request URL, method, path, route, IP address, and user agent to events captured during the request.

Register the integration after you create your Flask app and PostHog client:

app.py

from posthog.integrations.flask import PosthogFlaskIntegration

PosthogFlaskIntegration(
    app,
    client=posthog,
    capture_exceptions=True,
)

Setting capture_exceptions=True captures unhandled Flask exceptions. Set it to False for request enrichment without automatic exception capture. If you omit it, the integration inherits the client's enable_exception_autocapture setting.

You can also provide:

  • request_filter to skip both enrichment and automatic exception capture for selected requests

  • extra_properties to add application-specific properties to the request context

  • trust_tracing_headers to accept PostHog session and distinct ID headers

If you're using PostHog JavaScript Web on the frontend, configure tracing_headers for your Flask backend hostname so browser requests include the session and distinct ID headers.

The integration ignores these headers by default because clients can control them. Set trust_tracing_headers=True when registering the integration to accept them as analytics context. Don't use them for authentication or authorization.

Identify the request context from your route when you have an authenticated user ID:

from flask import session
from posthog import identify_context

@app.route("/api/dashboard", methods=["POST"])
def api_dashboard():
    user_id = session.get("user_id")
    if user_id:
        identify_context(str(user_id))

    posthog.capture("dashboard_api_called")

    return "", 204

Events captured without a context or explicit distinct_id are sent as anonymous events with an auto-generated distinct_id. See the Python SDK docs for more details.

Error tracking

PosthogFlaskIntegration captures unhandled exceptions when you set capture_exceptions=True or enable exception autocapture on its client. It doesn't capture expected HTTP exceptions or exceptions consumed by your application's error handlers.

Call capture_exception() from a custom error handler when you want to report a handled exception:

from flask import Flask, jsonify
from posthog import Posthog

app = Flask(__name__)
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:

Supported versions

These docs cover version 7.x of the PostHog Python SDK, which requires Python 3.10 or higher. Python 3.9 is no longer supported on 7.x.x and higher — pin to the 6.x line with pip install 'posthog<7', where 6.9.3 is the final release.

Everything on this page works the same way on 6.9.3. Event capture, the context API (new_context, identify_context, set_context_session), and PosthogContextMiddleware are identical on 6.9.3 and 7.0.0 — 7.0.0 only dropped Python 3.9 and bumped the optional LLM provider SDKs. That includes the middleware identifying the request context from the X-POSTHOG-DISTINCT-ID header and falling back to the authenticated user, which behaves the same across both lines.

Later 7.x releases add what the 6.x line does not receive, such as the Celery integration, tracing header sanitization, and set_context_device_id. They also changed the middleware's own captured properties: 7.x sends the request IP as $ip, where 6.9.3 sends it as $ip_address, and 7.x additionally captures $request_path, $raw_user_agent, and the authenticated user's email.

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 MCP server, Needs Python, Needs Node.js

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Attribution and licence

Created by
PostHog
Publisher
PostHog (Official)
Source
PostHog/skills · skills/omnibus/instrument-product-analytics · commit a5d30e7
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
Synced

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