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Event Watcher Event Watcher × Stack Builder

Scan Any Site. Build a Stack Diagram in Three Clicks.

Start building your Martech stack easier than before by using Rune Andersen’s Event Watcher Chrome extension. Scan what tracking scripts and pixels are on the site, export the data, and import it here. Getting started is as easy as 1, 2, 3. Thanks to Rune for adding this feature to his extension.

Install free on Chrome Open Stack Builder

Free · Made by Rune Andersen

Event Watcher detecting tracking platforms on a site, with Save as MartechStack Builder JSON highlighted, alongside the Stack Builder canvas

As easy as 1, 2, 3

From "I wonder what they’re running" to a working stack diagram in under a minute.

1

Install Event Watcher

Free Chrome extension from the Web Store. Opens as a tab in DevTools; no account needed.

Install from Chrome Web Store →
2

Scan + Export

Visit any site, open DevTools → Event Watcher. The extension classifies 600+ platforms as the page loads. Click Save as MartechStack Builder JSON.

Tag managers, pixels, analytics, CDPs, CMPs, session replay — all detected from real network signals.

3

Import into Stack Builder

In Stack Builder: File → Import from JSON. Pick the file and the stack diagram appears on the canvas, ready to edit and save.

Open Stack Builder →

600+ platforms recognized

Event Watcher sorts what it detects into categories. Some examples, as listed by Event Watcher:

Tag Managers

GTM, Tealium iQ, Adobe Launch, Segment, Rudderstack

Analytics

GA4, Adobe Analytics, Amplitude, Mixpanel, Heap

Advertising

Meta, LinkedIn, TikTok, Google Ads, Snapchat, Pinterest

CDPs

Segment, mParticle, Tealium, RudderStack, Hightouch

Consent (CMP)

OneTrust, Cookiebot, Didomi, Usercentrics, Sourcepoint

Session Replay

FullStory, Hotjar, ContentSquare, Clarity, LogRocket

A/B Testing

Optimizely, VWO, Dynamic Yield, Adobe Target

Server-side / SDKs

Stape, Addingwell, custom collectors, server containers

Event Watcher’s platform list grows with each release. See the full list at eventwatcher.dev.

Three ways teams use this combo

For consultants

Pre-kickoff client audits

Walk into the first meeting with the client’s front-end stack already on the canvas. Scan their site, import, then run the Evaluate tab for a first grade.

For in-house teams

Reality-check the spreadsheet

Compare what’s actually firing on your production site against what your "tools list" says. Find the rogue pixel nobody owns.

For competitive research

Map a competitor's stack

Scan a competitor’s site and see what their browser-side stack runs, laid out as an architecture diagram you can annotate.

Made by Rune Andersen

Rune is a Copenhagen-based developer building tools for Martech and analytics debugging. Event Watcher is free and actively maintained. Rune built the Save as MartechStack Builder JSON export into Event Watcher, and we’re grateful for the partnership.

Visit eventwatcher.dev Install on Chrome

Frequently Asked Questions

What is Event Watcher?
A free Chrome DevTools extension by Rune Andersen (Copenhagen) that recognizes 600+ tracking platforms on a website: tag managers, analytics, ad pixels, CDPs, consent tools, session replay, A/B testing. It watches the page as it loads, classifies what it sees, and lets you export the result. Event Watcher is Rune's product, not ours; details are on eventwatcher.dev.
Does it cost anything?
No. Event Watcher is free on the Chrome Web Store, and importing the file into Stack Builder works on the Free plan.
What gets imported into my stack diagram?
Event Watcher writes the file; Stack Builder loads its nodes and connections as they are. Detected platforms arrive as nodes, and where Event Watcher sees how they are wired (page → tag manager → vendor tool) those arrive as connections. You land on a canvas with the basics in place, ready to refine.
How accurate is the detection?
Event Watcher detects from signals such as script URLs, network requests and data layer pushes, so it reports what is actually loading, not what a tools list says. It can only see what runs in the browser: server-side tools and back-office systems will not appear. You can edit anything after import.
Do I need a Stack Builder account to import?
Saving needs a free account. The Free plan includes 3 cloud saves, enough to try the flow.
Will Event Watcher see private data?
Per eventwatcher.dev, event processing happens locally in your browser, the URLs you visit are never collected, and its optional usage analytics can be turned off. The file you export describes detected platforms and how they connect. Check eventwatcher.dev for the current privacy policy.
Can I use this on client sites or just my own?
Either. It is useful for scoping a client stack before kickoff, or for checking what is actually deployed against what the spreadsheet says. The extension sees only what a visitor's browser sees.

Scan, export, import — in under a minute

Free Chrome extension plus a free Stack Builder account: a quick path from a URL to a working Martech architecture diagram.

Install Event Watcher Open Stack Builder

No credit card required. Free plan available.