Cardano surges 30% on x402 payment test, XRP rises 22%

Cardano climbed roughly 30% in a single week, jumping from $0.19 on September 17 to an intraday high of $0.26 on September 23. The catalyst: the Cardano Foundation quietly integrated native support for the x402 payment protocol into its official SDK around September 21, then successfully tested it on the pre-production testnet. XRP, meanwhile, broke above $1.60 on a separate but overlapping wave of momentum, posting an approximate 22% gain tied largely to the Federal Reserve’s interest rate decision on September 16. What is x402, and why does it matter The x402 protocol borrows its name from HTTP status code 402, “Payment Required.” That status code has existed since the early days of the internet but was never widely implemented. It was essentially a placeholder for a future where browsers could handle payments natively. Originally introduced by Coinbase in 2025, the x402 standard is now governed by the Linux Foundation. Its purpose is straightforward: enable automated, pay-per-use microtransactions for AI applications without requiring traditional accounts or payment processors. For Cardano, the integration means ADA (or any Cardano-native token) can serve as the settlement layer...