Sardine gives merchants a tool to see the human behind an AI agent
Sardine said that fraud systems stop purchases by AI agents that are not fraud. The agents come from data centers, and the systems read them as a bot.
Sardine, a firm that stops fraud, launched Know Your Human. This protocol sends the device data and the IP address of a customer to a merchant. It does this when an AI agent makes a purchase for that customer. The merchant can then know the human behind the agent. Sardine gave no rate of purchases that fraud systems stopped.
How it works
The agent sends the device identifier and the IP address of the customer in some HTTP headers. At checkout, the merchant asks Sardine for these data and checks the human.
The merchant can also send the customer a text message with an address. The address opens a maximum of 3 times. It stops after 5 minutes.
The reason
Sardine connects the tool to card rules for disputes. In the Visa Acquirer Monitoring Program, fraud reports and disputes count in the ratio of a merchant. Sardine said that agents remove the device data that merchants use as proof in a dispute.
What is not known
Sardine gave no test results and no names of customers. It looks for partners in agent builders and merchants. No merchant is a user at this time.
Insight: Two ways to prove who is behind an agent
Descope released Envoy on 4 November 2026. Envoy gives each agent a different identity from the customer. Sardine does the opposite: it sends the device data of the human to the merchant. American Express wants agents on its list. This reads as a race to select who checks an agent, and the first vendor in use can collect a toll on each purchase. Leaders in retail must know which proof their fraud vendor accepts.
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