x402 vs L402 - what's the difference?
L402 is an earlier payment protocol from Lightning Labs that uses Bitcoin's Lightning Network for settlement and LSAT (Lightning Service Authentication Tokens) for auth. x402 is chain-agnostic but in practice settles on Base, Solana, and other low-fee EVM or SVM chains using USDC. L402 has the brand recognition of Bitcoin and the atomic guarantees of Lightning; x402 has stablecoin pricing, broader chain support, and a simpler header-only integration. Both protocols can coexist - a server can advertise multiple payment options in a single 402 response.