Coinbase and Stripe are vying for dominance in the emerging AI-driven payment protocol space, as traditional web commerce models face disruption. Coinbase's x402 and Stripe's MPP are leveraging the long-dormant HTTP 402 status code to facilitate micropayments, a concept envisioned in 1996 but hindered by high transaction fees and lack of infrastructure. With advancements in stablecoins and Layer 2 networks, these protocols aim to cater to the machine economy, where AI agents conduct transactions without human intervention. Coinbase's x402, launched in May 2025, focuses on a cryptocurrency-only approach, offering zero protocol fees and open-source flexibility. In contrast, Stripe's MPP, introduced in March 2026, integrates fiat payments and compliance features, targeting enterprise-grade applications. Both protocols are part of a broader ecosystem, with Visa and Mastercard also entering the market by leveraging their existing infrastructure to support agent payments. As the AI agent market grows, the success of these protocols will depend on their ability to navigate regulatory challenges and gain enterprise adoption.