Coinbase introduces x402: stablecoin payments over HTTP 402

An open protocol that turns Payment Required into a machine-payable API primitive.

On 6 May 2025 Coinbase Developer Platform published x402. Servers return HTTP 402 with payment requirements; clients retry with a signed payment, typically USDC on cheap L2s such as Base. The announcement explicitly targets APIs, apps and AI agents. Documentation and a reference implementation were pointed at x402.org and GitHub.

Why it matters

This is the commercial priority-zero rail for Foundry and the centre of zFinia’s payment-rail coverage. It revives a reserved HTTP status as an internet-native checkout for machines.

Source: Coinbase Developer Platform

First-party interest: Foundry operates in this market.

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