Mastercard opened developer APIs, SDKs and a sandbox for Agent Pay for Machines (AP4M) on October 21, 2026. The tools enable autonomous AI agents on Amazon Bedrock to make multi-merchant micropayments over x402 using off-chain signed vouchers. The launch follows Coinbase Developer Platform’s report that cumulative x402 payments across Base and Solana had exceeded 100 million by October. The x402 protocol uses an HTTP 402 response to tell an agent what a service costs and how to pay. Its growing infrastructure includes a Linux Foundation-governed foundation, while alternative approaches use Lightning payments or existing processor rails. Transaction counts, however, do not establish how much genuine agent-led commerce is taking place. TRM Labs found a much smaller pool of plausible commercial trade after screening out other activity. Security questions also remain, including whether a service can receive payment without delivering its output. Developers therefore face choices about settlement, spending controls and proof of service.