I Built a Paid API That AI Agents Use Autonomously

The author built FinSight, a financial portfolio analytics API where AI agents autonomously pay per call using USDC via the Machine Payments Protocol (MPP). The API offers five endpoints (risk profiling, rebalancing, diversification, stress testing, full report) and uses HTTP 402 challenges handled by the mppx SDK, making payment integration minimal. The stack runs on Cloudflare Workers with Tempo and Stripe's MPP enabling sub-second blockchain settlement.