How to Route x402 Payments Across Multiple Chains (Save 90%+ on Fees)

Your AI agent just got a 402 Payment Required response. It needs to pay — but on which chain? If it picks Base, the fee is $0.003. If it picks Polygon, $0.0075. If it picks Stellar, $0.00001. If it picks Ethereum L1... $3.50. That's a 350,000x difference for the same $0.10 USDC transfer. Most agents today pay on whatever chain the server lists first. At 10,000 payments per day, that's the difference between $0.10/day and $350/day in fees alone. Routex fixes this. It evaluates fees across all available chains in real time and picks the cheapest one — automatically, on every single payment. The x402 Protocol (Quick Primer) x402 is an open protocol by Coinbase that enables HTTP-native payments. When a server wants payment, it returns: HTTP/1.1 402 Payment Required The response body lists accepted chains, amounts, and recipient addresses. The client pays, attaches proof, and retries. Simple. The problem: the 402 response often lists multiple chains. The client has to choose. Without a rout