What is Cookie stuffing?

The fraudster loads a merchant’s tracking link invisibly, for example in a hidden image, iframe or script, or through a browser extension. The visitor never sees the ad, but the affiliate cookie is set. If that person later buys from the merchant for any reason, the commission goes to the fraudster.

It hurts merchants, who pay for sales they would have made anyway, and honest affiliates, whose real referrals get overwritten under last-click attribution inside the cookie window.

Every reputable program bans it, and it has led to lawsuits and criminal cases. Networks detect it by comparing clicks with impressions and by looking for conversions with impossibly short or missing click paths. Legitimate affiliates should only set cookies through clear, visible links.