What Is the Meta Pixel?

The Meta Pixel is a tracking tag that Meta (Facebook/Instagram) provides for advertisers to measure ad performance on their website. It transmits page views, event data, URL parameters, and behavioral signals back to Meta's ad systems, and, through a feature called Advanced Matching, can also capture form field data like email addresses.

The Meta Pixel is one of the most widely deployed tags on the web, and one of the most scrutinized in recent privacy enforcement, because of how much it captures by default. Its Advanced Matching feature watches for a user typing an email or phone number into any form field on the page, not just Meta’s own forms, and can transmit that data even when Hashing is applied, since hashed personal data is still PII under both GDPR and CCPA. Testing what a Meta Pixel actually sends, rather than assuming it behaves as documented, is the only way to know if it’s compliant on a given site.