Agentic Commerce Protocol

OpenAI and Stripe announced the Agentic Commerce Protocol on 29 September 2025, and it has been operational since that month. Its job is narrow: connect an agent to a merchant across discovery, cart and payment. Max Thilén's 2026 guide details the shape of that connection: a structured product feed, five REST endpoints for checkout, and a 4% commission per transaction on top of Stripe processing. The buyer never leaves the conversation, and Stripe settles the payment through a shared token so the agent never sees card data. Etsy and Walmart run it; Amazon does not, having chosen Rufus and "Buy for Me" instead.

The alias «ACP» is where the trouble starts. Didier Girard's note of 2 August 2026 documents three unrelated protocols sharing those three letters, and a search of his own watch base returned twelve hits, all on the commerce protocol, none on Zed's Agent Client Protocol. The rule he adopted from it: index the full name, treat the acronym as an alias only.

Two readings of the protocol compete in the sources. Nicolas Marette treats ACP and Google's UCP as infrastructure merchants must prepare for now, down to Merchant Center attributes. Sam Ragsdale calls both of them the AOL of agentic commerce: better UX inside a walled garden, a dead end for anything permissionless. Stripe's own Dan Hill supplies the awkward middle, writing in April 2026 that machine payment protocols are still gaining adoption and that agents need today's payment rails, then shipping a Link wallet that requires human approval on every single transaction.