x402 Protocol
An open payment protocol based on the HTTP 402 status code that enables AI agents and other software clients to automatically pay for API calls per request using cryptocurrencies such as USDC, without requiring accounts, API keys, or traditional checkout flows, thereby enabling autonomous machine-to-machine settlement.
Core Facts
x402 is an open protocol that reuses the 402 status code (Payment Required) from the HTTP protocol, enabling software (especially AI Agents) to call APIs on a per-request pay-as-you-go basis and settle directly with cryptocurrency (typically USDC), without requiring accounts, API keys, or traditional checkout pages.
The x402 protocol lets a server request stablecoin payment via the HTTP 402 status code before returning a resource, and it is already live and governed by the x402 Foundation under the Linux Foundation.
Timeline (last 90 days)
The x402 protocol lets a server request stablecoin payment via the HTTP 402 status code before returning a resource, and it is already live and governed by the x402 Foundation under the Linux Foundation.
The tool get_mycelium_snapshot returns an x402 payment request, containing x402Version: 2, error: Payment required, with a payment scheme of exact, a network of Solana mainnet, an amount of 50000 units of USDC (i.e., $0.05), and an asset of USDC.
In the x402 response, the feePayer field indicates that the facilitator will bear the Gas fees, so the Agent only needs to hold USDC to complete payment and does not need to maintain a SOL balance.
The x402 protocol was proposed by Coinbase in 2025.
The marginal cost of blockchain settlement is mainly reflected in Gas fees rather than proportional commissions, and x402's facilitator model can further externalize this portion of the cost.
x402 is an open protocol that reuses the 402 status code (Payment Required) from the HTTP protocol, enabling software (especially AI Agents) to call APIs on a per-request pay-as-you-go basis and settle directly with cryptocurrency (typically USDC), without requiring accounts, API keys, or traditional checkout pages.
The Facilitator (settlement party) is a key component in the x402 architecture, responsible for verifying payment signatures submitted by Agents and broadcasting transactions on the blockchain, allowing API providers to receive instant proof of payment without running their own blockchain nodes.
In the x402 protocol flow, when an AI agent requests a paid resource, the server returns a 402 status, whereupon the agent automatically completes payment authorization and re-sends the request, with no human intervention required throughout.
Agent Code Payments currently supports the X402 protocol, a modernized implementation of the HTTP 402 status code.
All Facts (9)
x402 is an open protocol that reuses the 402 status code (Payment Required) from the HTTP protocol, enabling software (especially AI Agents) to call APIs on a per-request pay-as-you-go basis and settle directly with cryptocurrency (typically USDC), without requiring accounts, API keys, or traditional checkout pages.
65%Partially VerifiedThe x402 protocol lets a server request stablecoin payment via the HTTP 402 status code before returning a resource, and it is already live and governed by the x402 Foundation under the Linux Foundation.
80%UnverifiedThe tool get_mycelium_snapshot returns an x402 payment request, containing x402Version: 2, error: Payment required, with a payment scheme of exact, a network of Solana mainnet, an amount of 50000 units of USDC (i.e., $0.05), and an asset of USDC.
50%UnverifiedIn the x402 response, the feePayer field indicates that the facilitator will bear the Gas fees, so the Agent only needs to hold USDC to complete payment and does not need to maintain a SOL balance.
50%UnverifiedThe x402 protocol was proposed by Coinbase in 2025.
50%UnverifiedThe marginal cost of blockchain settlement is mainly reflected in Gas fees rather than proportional commissions, and x402's facilitator model can further externalize this portion of the cost.
50%UnverifiedThe Facilitator (settlement party) is a key component in the x402 architecture, responsible for verifying payment signatures submitted by Agents and broadcasting transactions on the blockchain, allowing API providers to receive instant proof of payment without running their own blockchain nodes.
50%UnverifiedIn the x402 protocol flow, when an AI agent requests a paid resource, the server returns a 402 status, whereupon the agent automatically completes payment authorization and re-sends the request, with no human intervention required throughout.
50%UnverifiedAgent Code Payments currently supports the X402 protocol, a modernized implementation of the HTTP 402 status code.
50%