Setting the file. One moment.
Chapter 47 · Instrument Integration
Subchapter 47.3
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PostHog makes it easy to get data about traffic and usage of your Astro app. Integrating PostHog into your site enables analytics about user behavior, custom events capture, session recordings, feature flags, and more.
This guide walks you through integrating PostHog into your Astro app using the JavaScript Web SDK (opens in a new tab).
Install PostHog for Astro in seconds with our wizard by running this prompt with LLM coding agents (opens in a new tab) like Cursor and Bolt, or by running it in your terminal.
npx @posthog/wizard@latest
Or, to integrate manually, continue with the rest of this guide.
In your src/components folder, create a posthog.astro file:
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cd ./src/components
# or 'cd ./src && mkdir components && cd ./components' if your components folder doesnt exist
touch posthog.astroIn this file, add your Web snippet which you can find in your project settings (opens in a new tab). Be sure to include the is:inline directive to prevent Astro from processing it (opens in a new tab), or you will get Typescript and build errors that property ‘posthog’ does not exist on type ‘Window & typeof globalThis’.
posthog.astro
PostHog AI
<script is:inline>
!function(t,e){var o,n,p,r;e.__SV||(window.posthog=e,e._i=[],e.init=function(i,s,a){function g(t,e){var o=e.split(".");2==o.length&&(t=t[o[0]],e=o[1]),t[e]=function(){t.push([e].concat(Array.prototype.slice.call(arguments,0)))}}(p=t.createElement("script")).type="text/javascript",p.crossOrigin="anonymous",p.async=!0,p.src=s.api_host+"/static/array.js",(r=t.getElementsByTagName("script")[0]).parentNode.insertBefore(p,r);var u=e;for(void 0!==a?u=e[a]=[]:a="posthog",u.people=u.people||[],u.toString=function(t){var e="posthog";return"posthog"!==a&&(e+="."+a),t||(e+=" (stub)"),e},u.people.toString=function(){return u.toString(1)+".people (stub)"},o="capture identify alias people.set people.set_once set_config register register_once unregister opt_out_capturing has_opted_out_capturing opt_in_capturing reset isFeatureEnabled onFeatureFlags getFeatureFlag getFeatureFlagPayload reloadFeatureFlags group updateEarlyAccessFeatureEnrollment getEarlyAccessFeatures getActiveMatchingSurveys getSurveys getNextSurveyStep onSessionId".split(" "),n=0;n<o.length;n++)g(u,o[n]);e._i.push([i,s,a])},e.__SV=1)}(document,window.posthog||[]);
posthog.init('<ph_project_token>', {
api_host:'https://us.i.posthog.com',
defaults: '2026-01-30'
})
</script>Using with Astro’s view transitions (ClientRouter)
If you’ve opted in to Astro’s <ClientRouter> component for client-side navigation, you’ll need to add an initialization guard to prevent PostHog from running multiple times during page transitions.
Update your posthog.astro file to wrap the snippet with a check:
posthog.astro
PostHog AI
---
// src/components/posthog.astro
---
<script is:inline>
if (!window.__posthog_initialized) {
window.__posthog_initialized = true;
!function(t,e){var o,n,p,r;e.__SV||(window.posthog=e,e._i=[],e.init=function(i,s,a){function g(t,e){var o=e.split(".");2==o.length&&(t=t[o[0]],e=o[1]),t[e]=function(){t.push([e].concat(Array.prototype.slice.call(arguments,0)))}}(p=t.createElement("script")).type="text/javascript",p.crossOrigin="anonymous",p.async=!0,p.src=s.api_host+"/static/array.js",(r=t.getElementsByTagName("script")[0]).parentNode.insertBefore(p,r);var u=e;for(void 0!==a?u=e[a]=[]:a="posthog",u.people=u.people||[],u.toString=function(t){var e="posthog";return"posthog"!==a&&(e+="."+a),t||(e+=" (stub)"),e},u.people.toString=function(){return u.toString(1)+".people (stub)"},o="capture identify alias people.set people.set_once set_config register register_once unregister opt_out_capturing has_opted_out_capturing opt_in_capturing reset isFeatureEnabled onFeatureFlags getFeatureFlag getFeatureFlagPayload reloadFeatureFlags group updateEarlyAccessFeatureEnrollment getEarlyAccessFeatures getActiveMatchingSurveys getSurveys getNextSurveyStep onSessionId".split(" "),n=0;n<o.length;n++)g(u,o[n]);e._i.push([i,s,a])},e.__SV=1)}(document,window.posthog||[]);
posthog.init('<ph_project_token>', {
api_host: 'https://us.i.posthog.com',
defaults: '2026-01-30',
capture_pageview: 'history_change'
})
}
</script>Without this guard, ClientRouter‘s soft navigation can re-execute the inline script during page transitions, causing a stack overflow error. The capture_pageview: 'history_change' option ensures pageviews are tracked automatically as users navigate.
The next step is to a create a Layout (opens in a new tab) where we will use posthog.astro. Create a new file PostHogLayout.astro in your src/layouts folder:
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cd .. && cd .. # move back to your base directory if you're still in src/components/posthog.astro
cd ./src/layouts
# or 'cd ./src && mkdir layouts && cd ./layouts' if your layouts folder doesn't exist yet
touch PostHogLayout.astroAdd the following code to PostHogLayout.astro:
PostHogLayout.astro
PostHog AI
---
import PostHog from '../components/posthog.astro'
---
<head>
<PostHog />
</head>Lastly, update index.astro to wrap your existing app components with the new Layout:
index.astro
PostHog AI
---
import PostHogLayout from '../layouts/PostHogLayout.astro';
---
<PostHogLayout>
<!-- your existing app components -->
</PostHogLayout>Identifying users is required. Call
posthog.identify('your-user-id')after login to link events to a known user. This is what connects frontend event captures, session replays (opens in a new tab), LLM traces (opens in a new tab), and error tracking (opens in a new tab) to the same person — and lets backend events link back too.See our guide on identifying users (opens in a new tab) for how to set this up.
Set up a reverse proxy (recommended)
We recommend setting up a reverse proxy (opens in a new tab), so that events are less likely to be intercepted by tracking blockers.
We have our own managed reverse proxy service (opens in a new tab), which is free for all PostHog Cloud users, routes through our infrastructure, and makes setting up your proxy easy.
If you don’t want to use our managed service then there are several other options for creating a reverse proxy, including using Cloudflare (opens in a new tab), AWS Cloudfront (opens in a new tab), and Vercel (opens in a new tab).
Grouping products in one project (recommended)
If you have multiple customer-facing products (e.g. a marketing website + mobile app + web app), it’s best to install PostHog on them all and group them in one project (opens in a new tab).
This makes it possible to track users across their entire journey (e.g. from visiting your marketing website to signing up for your product), or how they use your product across multiple platforms.
Add IPs to Firewall/WAF allowlists (recommended)
For certain features like heatmaps (opens in a new tab), your Web Application Firewall (WAF) may be blocking PostHog’s requests to your site. Add these IP addresses to your WAF allowlist or rules to let PostHog access your site.
EU: 3.75.65.221, 18.197.246.42, 3.120.223.253
US: 44.205.89.55, 52.4.194.122, 44.208.188.173
These are public, stable IPs used by PostHog services (e.g., Celery tasks for snapshots).
For any technical questions for how to integrate specific PostHog features into Astro (such as analytics, feature flags, A/B testing, surveys, etc.), have a look at our JavaScript Web SDK docs (opens in a new tab).
Alternatively, the following tutorials can help you get started:
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