Agentic Payments Landscape Expands as Four Key Protocols Emerge

The agentic payments landscape is rapidly evolving, with four key protocols emerging as dominant players: x402, AP2, MPP, and ACP.

x402 focuses on settlement, leveraging the dormant HTTP 402 status code to enable agents to request resources, receive pricing details, and pay in stablecoins like USDC. It's ideal for machine-to-machine transactions, such as API calls or compute jobs. As of Q1 2026, x402 had processed over 100 million cumulative transactions on Base.

The AP2 protocol, developed by Google, sits at the authorization layer and enables cryptographically signed mandates to verify user intent, agent actions, and payment approvals. This protocol doesn't move money but provides verifiable trust for merchants and networks in agent-driven transactions.

MPP, co-authored by Stripe and Tempo, excels at session-based payments, allowing agents to establish spending limits and stream micropayments over time without requiring an on-chain transaction for every interaction. ACP, developed by OpenAI and Stripe, standardizes agent-to-merchant checkouts and focuses on consumer-oriented purchases.

The protocols often appear competitive but largely address different layers of a transaction: settlement, authorization, session-based payments, and checkout. Industry players are hedging their bets by supporting multiple protocols, with Visa and Mastercard deeply involved in both x402 and AP2.