PostHog
PostHog is the open-source, all-in-one product analytics platform.
What detecting PostHog tells you about a site
PostHog is a product-analytics and feature-flag platform, detected from the SDK it injects rather than any server signal. The tells are a script loaded from app.posthog.com / *.i.posthog.com (or a self-hosted reverse-proxy path), a window.posthog global once it initialises, and ph_* cookies/localStorage keys capturing the distinct ID. Spotting it signals a product-led team that instruments user behaviour, runs experiments and gates features with flags — and, given PostHog's open-source self-host option, often one that cares about owning its analytics data rather than handing it to a third party.
PostHog in a real-world stack
When you find PostHog, it rarely travels alone. Frequently alongside a SPA framework plus session-replay, A/B testing and feature-flagging all consolidated into PostHog itself.
About
PostHog is the open-source, all-in-one product analytics platform.
Categories: Analytics
Quick facts
Detection methodology for Analytics
Analytics SDKs are usually loaded from a vendor-controlled CDN (`googletagmanager.com`, `google-analytics.com`, `cdn.segment.com`, `cdn.amplitude.com`, `eu.i.posthog.com`) and expose a global with a recognisable surface. We catch the script src URL plus the global plus — when a sourcemap is available — the exact `node_modules/<sdk>/package.json` version. Tracker isolation prevents these vendor libraries from polluting the surrounding stack readings.
How we detect PostHog
Sourcemap Explorer carries 3 fingerprint signals for PostHog, spread across 2 channels — javascript global and script src url. The exact patterns are listed below, and you can replay each one in Chrome DevTools to confirm a match by hand.
Each signal alone is rarely conclusive — Sourcemap Explorer cross-references all of them and weights by confidence. You can reproduce any of these checks yourself in Chrome DevTools.
Window-level global the technology installs on page. Reproducible by typing the path into the DevTools console.
window.__PosthogExtensions__
window.posthog
Script URL pattern. Typically a CDN host or chunk path that ships with the technology.
app\.posthog\.com/
FAQ
How do I check if a website is using PostHog?
Open the page in Chrome, click the Sourcemap Explorer toolbar icon, and read the Stack tab. PostHog's specific fingerprints here are javascript global and script src url, and the popup flags PostHog whenever any combination of them is found. The same checks can be reproduced manually in DevTools — see the "How we detect" section above.
What PostHog version can Sourcemap Explorer detect?
PostHog ships as a hosted analytics rather than a bundled npm package, so version-specific detection isn't always possible. Where the platform leaks a version in response headers (`X-Powered-By`, `Server`, generator meta tags) we surface it; otherwise we report presence only.
Is PostHog open source?
Yes, PostHog is open source. The license details are listed on the official site (https://posthog.com), and the codebase typically lives on a public source-control host.
How much does PostHog cost?
PostHog's pricing model is documented as: freemium, payg. Detection is independent of the pricing tier — Sourcemap Explorer flags the technology by its fingerprints, regardless of which paid plan a site is on. See the official site for the current pricing page.
Where can I read more about PostHog?
Official site: https://posthog.com. For Sourcemap Explorer's detection guide, see the deep-dive link below or the related guides in the cross-link section.
Keep reading on Sourcemap Explorer
Practical guides
Alternative tools
Detected by Sourcemap Explorer
Open the popup on any page running PostHogand you'll see the exact version pulled from the bundled package.json when sourcemaps are exposed.