Email Tracking Pixel Detector

About this tool

Email Tracking Pixel Detector inspects raw email source or HTML markup for the remote assets that can report when a message is opened. It looks for tiny 1×1 or 0×0 images, CSS-hidden images, known email-service and sales-tool tracking hosts, open/pixel/beacon URL paths, unique recipient IDs in query strings, CSS background-image beacons, and prefetch/preload links.

Everything runs locally in your browser. The detector never fetches the image, follows a redirect, resolves DNS, opens a mailbox, or uploads your email. A TRACKED result means the pasted markup declares at least one high-confidence open tracker. LIKELY_TRACKED means a remote asset has structural tracking signals but no known vendor match. REMOTE_CONTENT means the email would contact a remote host even though no tracker-specific signal was found.

Worked example

Paste this HTML:

<img src="https://track.hubspot.com/[email protected]&id=abc123456789abcdef" width="1" height="1" style="display:none">

The summary reports TRACKED, lists track.hubspot.com as a host contacted on open, and explains the signals: known tracker domain, tiny pixel, hidden CSS, tracking path, and unique ID query.

Set Report to Hosts only when you want a paste-ready list for a mail rule, firewall, or content blocker. Add private ESP or CDN hosts in Extra tracker domains when your organization rewrites tracking links through a custom domain.

Limits and edge cases

• The vendor table is a curated snapshot. Unknown hosts are still flagged when their markup looks like a tracker, and you can add custom hosts with the vendors field.
• Raw .eml input is scanned as pasted source. Encoded MIME parts that do not expose their HTML after export may need to be decoded by your mail client first.
• The tool does not perform network I/O, so it cannot inspect HTTP headers, ETags, cookies, redirects, or live reputation feeds.
• A CLEAN result only means no remote image/prefetch/link tracker was declared in the pasted markup. It cannot see content that your mail client would fetch or rewrite later.

FAQ