Circle and Proof demo AI agents proving identity and paying in USDC

Circle and Proof on Monday demonstrated a way for AI agents to prove who they act for and pay for what they buy, combining an open identity protocol with a stablecoin payment rail.

In the demo, an AI agent presents a Proof verified credential over Proof's open identity protocol, x401, and pays in USDC over x402, the open protocol for internet-native payments, from a Circle Agent Wallet, the companies said in a press release.

Both protocols borrow the semantics of HTTP status codes. x401, which Proof published in June, uses the web's 401 "Unauthorized" response so a site can tell an agent what proof of identity it needs. x402 uses the 402 "Payment Required" response so a site can tell an agent what payment it needs.

The flow is designed to be checked end to end: the Proof wallet presents a person's verified credential along with a signed credential for the purchase, the merchant verifies the signature against Proof's published public keys, the agent pays the merchant in USDC over x402 from a Circle Agent Wallet, and the order completes. Because one protocol answers who the agent is and the other answers how it pays, a business can pay an identity provider for each check on the spot.

"This demo shows that one exchange can provide both verified identity and payment," Proof founder and CEO Pat Kinsel said in the release. "That gives businesses a reason to say yes to agents instead of blocking them."

Circle VP of product Gagan Mac said identity and payments are closely linked in the agentic economy, adding that the two companies are continuing to explore how they come together "so businesses can trust the transactions agents make."

The demo builds on separate momentum. Proof announced on Oct. 15 that x401 supports Meta's Muse, ChatGPT dots, Grok, Claude and other assistants that support the Model Context Protocol, letting those agents prove who they represent and what they are authorized to do. The x402 Foundation launched in July as an open-governance body with 40 initial member organizations.

For merchants, the pitch is to replace blanket blocking of unknown bots with verification followed by a transaction. For Circle, it puts USDC and the Agent Wallet at the center of how agents pay.

What to watch next is adoption, and liability. The combination only matters if mainstream merchants and platforms integrate it, and it remains unclear how responsibility would be split among the identity provider, the payment provider and the merchant when an agent errs, overcharges or has its credential stolen.