OpenAI opens Instant Checkout and publishes ACP as an open standard

ChatGPT becomes a commerce client. Merchants keep their processor.

OpenAI’s 29 September 2025 note describes Instant Checkout powered by ACP, built with Stripe, and open-sources the protocol so other agents and merchants can implement checkout sessions. This is in-chat retail, not an API micropayment 402.

Why it matters

Agent commerce split: consumer checkout (ACP) versus machine API metering (x402/MPP). zFinia covers both without collapsing them.

Source: OpenAI

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