APEX: Agent Payment Execution Protocol Enables Per-Request API Monetization via HTTP 402

arXiv·medium signal

Researchers propose APEX, a framework for autonomous agents to pay for API access at the request level using the HTTP 402 status code, with programmatic spend governance policies. Unlike crypto-based approaches, APEX uses fiat payment rails (UPI), making it deployable in countries with strong real-time payment systems. As agents become economic actors invoking APIs and sequencing workflows, this addresses a fundamental infrastructure gap: how agents pay for services autonomously.