PROTOCOL · ACP
ACP — Agentic Commerce Protocol
The commerce-specific handshake between agents and merchants. Signed intents, negotiated terms, recorded receipts.
THE ANSWER
What is the Agentic Commerce Protocol (ACP)?
The Agentic Commerce Protocol (ACP) is a handshake spec from OpenAI and Stripe for agent-to-merchant commerce. It defines how an agent cryptographically signs an intent, negotiates terms with a merchant, and produces a receipt that the merchant, the human, and the payment network can all audit.
Why a new commerce protocol
Existing checkout flows presume three things: a cursor, a human, and a page. An agent has none of those. It arrives with a signed intent, a budget ceiling, and a willingness to negotiate. ACP is built for that agent.
OpenAI and Stripe proposed ACP in 2025 as a layer on top of conventional payment rails. It does not replace Stripe or Visa or ACH. It sits in front of them and teaches the merchant how to accept an agent-signed intent, negotiate terms, and emit a machine-readable receipt that ties the whole transaction to both the human principal and the agent acting on their behalf.
The handshake
- Intent. The agent produces a signed payload describing what it wants, from whom, with constraints (price ceiling, substitutions allowed, delivery window).
- Discovery. The merchant exposes its
agent-commerce.jsonmanifest so the agent knows what's available, the pricing tiers, the negotiation parameters. - Negotiation.The two sides exchange counter offers until they either converge or the agent abandons per the intent's rules.
- Settlement. Funds move through the underlying rail (Stripe, ACH, x402) and both parties sign the final receipt.
- Audit. Every step is hashable, re-verifiable, and persisted — ideally to a neutral gate like Aethelforge.
What Aethelforge adds
ACP specifies the handshake. It does not specify where the receipts go, who witnesses them, or how disputes unwind. Aethelforge answers those questions: we archive the signed intent, the counter-offer exchange, and the final settlement under a tenant-redacted ledger that either party can audit on demand. Humans stay in the loop by default — every high-value transaction can be gated behind an approval step surfaced to the principal.
A merchant that installs Forge SDK gets ACP support for free. Agents transacting through the Aethelforge gate use ACP under the hood whenever a negotiation is needed; plain static purchases route over x402 instead.
Why this matters
Agents buying from agents will only work at scale if the trust stack is auditable. ACP is the first protocol to treat that as a first-class requirement — not a bolt-on after the fact. Every transaction it mediates leaves a forensic trail. That trail is what makes a human comfortable letting their agent spend money in the first place.