x402
An open standard for HTTP-native programmatic payments using stablecoins, hosted by the x402 Foundation under the Linux Foundation.
x402 is the open protocol for HTTP-native programmatic payments using stablecoins. The flow is: a client requests a paid resource without a payment header; the server responds with HTTP 402 Payment Required and a JSON body listing one or more accepted payment requirements; the client signs a payment payload; the client retries with the X-PAYMENT header; the server verifies, settles via a facilitator, and returns the resource along with X-PAYMENT-RESPONSE.
Mission Control speaks x402 natively for every paid call. The protocol is hosted by the x402 Foundation under the Linux Foundation, which means it is a neutral standard that competitors can implement together — Mission Control, Coinbase Bazaar, Agentic.Market, individual SaaS vendors all use the same wire format.
x402 supports several extensions, two of which Mission Control relies on: payment-identifier (for safe retries / idempotency) and signed offers + receipts (for cryptographic proof of interaction).
- Payment-Identifier (x402 extension)— An x402 extension that lets buyers attach a stable identifier to retries so vendors can deduplicate payment processing.
- x402 Facilitator— A trusted third-party service that verifies and settles x402 payments on behalf of vendors who don't want to run their own settlement layer.
- Stablecoin— A cryptocurrency pegged to a fiat reference (typically USD) — the unit of account for x402 payments. USDC is the default in Mission Control.