Why x402 Uses Bitcoin SV A protocol engineering decision, not a blockchain preference When designing x402, the goal was simple: Create a protocol where payment becomes a native part of HTTP request execution. A client makes a request. If payment is required, the server returns 402 Payment Required. The client pays, proves payment, and retries the request. request → 402 challenge → payment → proof → execution No accounts. No API keys. No subscription ledgers. Just per-request settlement. This design places unusual requirements on the underlying settlement layer. The question quickly becomes: Which blockchain can actually support this model? The answer turns out to be: very few. article below