What Are Query Parameters?

Query parameters are the components of a URL that follow a question mark, for example [email protected], used to pass data between pages or to third-party systems. Because they're plainly visible in the URL, query parameters are a common and easily overlooked way for personal data to leak to tags or external servers.

A password-reset link, a pre-filled email field, or a tracking parameter appended by a marketing campaign can all carry personal data in a URL’s query string, and any tag that reads the full URL (which many do by default) picks that data up along with it. Payload Inspection is what catches this; a tag simply firing correctly tells you nothing about what’s riding along in the URL it read.