x402 Protocol
Open payment protocol that lets AI agents and APIs send instant stablecoin micropayments over HTTP using the 402 status code.
🛡️ AgentReady threat assessment
MAESTRO 7-layer threat model + OWASP AIVSS risk score for x402 Protocol, derived from its capabilities.
These scores are auto-generated from public information (the agent's own listing, docs, and repository) using the canonical OWASP AIVSS formula and the MAESTRO framework — an estimate for guidance, not a penetration test, audit, or certification. See the scoring methodology. Are you the vendor? Factual corrections are free.
Overview
x402 is an open, internet-native payment protocol that activates the long-reserved HTTP 402 “Payment Required” status code to handle payments directly inside web and API requests. It allows AI agents, apps, and APIs to charge and pay per request using stablecoins like USDC, removing the need for traditional API keys, subscriptions, or manual billing. Built as an open standard by Coinbase and deployed on chains such as Solana and Base, x402 supports low-cost, high-throughput micropayments suitable for agentic workflows, data APIs, model inference, and digital content. By embedding pricing, payment instructions, and proof of payment in normal HTTP flows, x402 enables fully autonomous, machine-to-machine commerce and a more granular, usage-based business model for online services.
Key features
- HTTP 402
- micropayments
- stablecoin payments
- USDC
- onchain payments
- machine-to-machine commerce
- AI agent commerce
- API monetization
- pay-per-use billing
- Solana
Use cases
- Monetizing APIs, AI models, and data services with pay-per-request or usage-based pricing instead of subscriptions.
- Enabling AI agents to autonomously pay for API calls, data, and compute using stablecoins over HTTP.
- Adding micropayments to web content such as articles, datasets, or tools without user accounts or OAuth flows.
- Building machine-to-machine payment flows for IoT devices, bots, and autonomous services.
- Experimenting with new pricing models like fine-grained metering and dynamic pay-per-use for digital services.