Cardano joins x402 standard to enable ADA agent payments

Cardano joined the x402 payment standard on September 21, enabling applications and autonomous AI agents to pay for online services directly in ADA and Cardano-native tokens, according to documentation from the Cardano Foundation's x402 implementation. x402 is an open HTTP payment standard originally created by Coinbase in 2025 before being moved under Linux Foundation governance. It revives the long-dormant HTTP 402 Payment Required status code, turning it into a functional payment handshake for automated transactions. When an AI agent requests a paid resource such as an API call or dataset, the service returns pricing details within the same request. The agent signs a transaction, a facilitator verifies and settles it on-chain, and the resource is delivered without accounts, API keys or traditional checkout screens. Cardano Foundation engineers built the client, server and facilitator components after the network's specification was accepted in June and merged into the official x402 repository around September 9.