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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/identify-users.md

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

Identify users

Canonical URL: https://posthog.com/docs/getting-started/identify-users

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).

On this page

  • How identify works

  • Best practices when using identify

  • Further reading

Linking events to specific users enables you to build a full picture of how they're using your product across different sessions, devices, and platforms.

This is straightforward to do when capturing backend events, as you associate events to a specific user using a distinct_id, which is a required argument.

However, in the frontend of a web or mobile app, a distinct_id is not a required argument — PostHog's SDKs will generate an anonymous distinct_id for you automatically and you can capture events anonymously, provided you use the appropriate configuration.

To link events to specific users, call identify:

Web
posthog.identify(
  'distinct_id',  // Replace 'distinct_id' with your user's unique identifier
  { email: '[email protected]', name: 'Max Hedgehog' } // optional: set additional person properties
);
Android
PostHog.identify(
    distinctId = distinctID, // Replace 'distinctID' with your user's unique identifier
    // optional: set additional person properties
    userProperties = mapOf(
        "name" to "Max Hedgehog",
        "email" to "[email protected]"
    )
)
iOS
PostHogSDK.shared.identify("distinct_id", // Replace "distinct_id" with your user's unique identifier
                           userProperties: ["name": "Max Hedgehog", "email": "[email protected]"]) // optional: set additional person properties
React Native
posthog.identify('distinct_id', { // Replace "distinct_id" with your user's unique identifier
    email: '[email protected]', // optional: set additional person properties
    name: 'Max Hedgehog'
})
Dart
await Posthog().identify(
  userId: 'distinct_id', // Replace "distinct_id" with your user's unique identifier
  userProperties: {
    'email': '[email protected]', // optional: set additional person properties
    'name': 'Max Hedgehog',
  },
);

Events captured after calling identify are identified events and this creates a person profile if one doesn't exist already.

Due to the cost of processing them, anonymous events can be up to 4x cheaper than identified events, so it's recommended you only capture identified events when needed.

How identify works

When a user starts browsing your website or app, PostHog automatically assigns them an anonymous ID, which is stored locally.

Provided you've configured persistence to use cookies or localStorage, this enables us to track anonymous users – even across different sessions.

By calling identify with a distinct_id of your choice (usually the user's ID in your database, or their email), you link the anonymous ID and distinct ID together.

Thus, all past and future events made with that anonymous ID are now associated with the distinct ID.

This enables you to do things like associate events with a user from before they log in for the first time, or associate their events across different devices or platforms.

Using identify in the backend

Although you can call identify using our backend SDKs, it is used most in frontends. This is because there is no concept of anonymous sessions in the backend SDKs, so calling identify only updates person profiles.

Best practices when using identify

1. Call identify as soon as you're able to

In your frontend, you should call identify as soon as you're able to.

Typically, this is every time your app loads for the first time, and directly after your users log in.

This ensures that events sent during your users' sessions are correctly associated with them.

You only need to call identify once per session, and you should avoid calling it multiple times unnecessarily.

If you call identify multiple times with the same data without reloading the page in between, PostHog will ignore the subsequent calls.

Identify users when the web SDK loads

If your app already knows the signed-in user when you initialize the JavaScript web SDK, the loaded callback is a convenient place to call identify. This identifies the user as soon as the SDK has loaded:

posthog.init('<ph_project_token>', {
    api_host: 'https://us.i.posthog.com',
    defaults: '2026-08-30',
    loaded: (posthog) => {
        if (currentUser?.id) {
            posthog.identify(currentUser.id, {
                email: currentUser.email,
                name: currentUser.name,
            })
        }
    },
})

In this example, currentUser represents user data already available from your authentication system. If your app loads the user asynchronously, call posthog.identify() as soon as that data becomes available instead.

2. Use unique strings for distinct IDs

If two users have the same distinct ID, their data is merged and they are considered one user in PostHog. Two common ways this can happen are:

  • Your logic for generating IDs does not generate sufficiently strong IDs and you can end up with a clash where 2 users have the same ID.

  • There's a bug, typo, or mistake in your code leading to most or all users being identified with generic IDs like null, true, or distinctId.

PostHog also has built-in protections to stop the most common distinct ID mistakes.

3. Reset after logout

If a user logs out on your frontend, you should call reset() to unlink any future events made on that device with that user.

This is important if your users are sharing a computer, as otherwise all of those users are grouped together into a single user due to shared cookies between sessions.

We strongly recommend you call reset on logout even if you don't expect users to share a computer.

You can do that like so:

Web
posthog.reset()
iOS
PostHogSDK.shared.reset()
Android
PostHog.reset()
React Native
posthog.reset()
Dart
await Posthog().reset();

If you also want to reset the device_id so that the device will be considered a new device in future events, you can pass true as an argument:

posthog.reset(true)
4. Person profiles and properties

You'll notice that one of the parameters in the identify method is a properties object.

This enables you to set person properties.

Whenever possible, we recommend passing in all person properties you have available each time you call identify, as this ensures their person profile on PostHog is up to date.

Person properties can also be set being adding a $set property to a event capture call.

$set and $set_once aren't stored on events

These properties only tell PostHog how to update person data during ingestion — they aren't kept on the stored event, so you can't filter, break down, or query events by them. To query the values you set, use person properties instead.

See our person properties docs for more details on how to work with them and best practices.

5. Use deep links between platforms

We recommend you call identify as soon as you're able, typically when a user signs up or logs in.

This doesn't work if one or both platforms are unauthenticated. Some examples of such cases are:

  • Onboarding and signup flows before authentication.

  • Unauthenticated web pages redirecting to authenticated mobile apps.

  • Authenticated web apps prompting an app download.

In these cases, you can use a deep link on Android and universal links on iOS to identify users.

  1. Use posthog.get_distinct_id() to get the current distinct ID. Even if you cannot call identify because the user is unauthenticated, this will return an anonymous distinct ID generated by PostHog.

  2. Add the distinct ID to the deep link as query parameters, along with other properties like UTM parameters.

  3. When the user is redirected to the app, parse the deep link and handle the following cases:

  • The mobile app is already authenticated. In this case, call posthog.alias() with the distinct ID from the web. This associates the two distinct IDs as a single person.

  • The mobile app is unauthenticated. In this case, call posthog.identify() with the distinct ID from the web so pre-login mobile events stay connected to the web session. When the user later logs in on mobile, call identify() again with your canonical user ID.

As long as you associate the distinct IDs with posthog.identify() or posthog.alias(), you can track events generated across platforms.

Here's an example implementation for handling deep links from web to mobile:

iOS
import PostHog

class DeepLinkIdentityManager {
    static let shared = DeepLinkIdentityManager()

    // MARK: - Deep Link Received

    func handleDeepLink(_ url: URL, isAuthenticatedOnMobile: Bool) {
        guard let webDistinctId = URLComponents(url: url, resolvingAgainstBaseURL: true)?
            .queryItems?.first(where: { $0.name == "ph_distinct_id" })?.value else {
            return
        }

        if isAuthenticatedOnMobile {
            // The mobile app already knows the current user.
            // Alias the incoming web distinct ID to that user.
            PostHogSDK.shared.alias(webDistinctId)
        } else {
            // Reuse the web distinct ID until login on mobile.
            PostHogSDK.shared.identify(webDistinctId)
        }
    }

    // MARK: - Login/Signup

    func handleLogin(canonicalUserId: String) {
        // Switch from the web distinct ID (or a mobile anon ID)
        // to your canonical user ID.
        PostHogSDK.shared.identify(canonicalUserId)
        // Set user properties, track signup event, etc.
    }

    func handleLogout() {
        PostHogSDK.shared.reset()
    }
}
Android
import android.net.Uri
import com.posthog.PostHog

object DeepLinkIdentityManager {

    // Deep Link Received

    fun handleDeepLink(uri: Uri, isAuthenticatedOnMobile: Boolean) {
        val webDistinctId = uri.getQueryParameter("ph_distinct_id") ?: return

        if (isAuthenticatedOnMobile) {
            // The mobile app already knows the current user.
            // Alias the incoming web distinct ID to that user.
            PostHog.alias(webDistinctId)
        } else {
            // Reuse the web distinct ID until login on mobile.
            PostHog.identify(webDistinctId)
        }
    }

    // Login/Signup

    fun handleLogin(canonicalUserId: String) {
        // Switch from the web distinct ID (or a mobile anon ID)
        // to your canonical user ID.
        PostHog.identify(canonicalUserId)
        // Set user properties, track signup event, etc.
    }

    fun handleLogout() {
        PostHog.reset()
    }
}

Further reading

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

Security

What our scanner noticed· Low risk

  • Instructions that use the network

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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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Download ZIP

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