USDC

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.

USDT and USDC account for the vast majority of the stablecoin market share.

Solana链上的USDC采用原生发行（Native USDC）而非跨链桥接

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.

SiteCheck offers 132 tools, all exposed through a single HTTP endpoint, priced between $0.001 and $0.01 per call, with payment in USDC via the x402 protocol, requiring no account, API key or subscription.

The logic of the batch settlement mechanism is: the agent opens a payment channel funded with USDC, authorizes requests one by one off-chain, and finally settles the cumulative total with a single on-chain transaction.

The payment field in a real unpaid 402 response contains: scheme: exact, network: eip155:8453 (Base), asset: USDC contract address, amount: 10000 (i.e. 0.01 USDC), payTo: receiving address, maxTimeoutSeconds: 120.

Stablecoins refer to crypto assets pegged to the value of a fiat currency (usually the US dollar), such as USDC and USDT, whose payment advantages lie in fast settlement, low cross-border costs, and strong programmability; the irreversibility of on-chain payments means that once a signature is broadcast, the transaction usually cannot be revoked, in contrast to the credit card chargeback mechanism.

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 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.

Reply Desk exposes a machine-readable /templates.json interface via the x402 payment protocol on the Base chain in USDC, charging $0.50 per fetch, with no account or API key required.

Polymarket is a decentralized prediction market built on the Polygon blockchain, where users use the USDC stablecoin to buy shares of event outcomes, with prices between 0 and 1 US dollar directly corresponding to the market-implied probability.

Payment parameters for the two endpoints: payTo=0xCa0a6c6Aa7A8F0D5893636CF166Ea2b44fb6500c, asset=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 (USDC on Base), network=eip155:8453, maxAmountRequired=500 atomic ($0.0005)

AI agents can make payments in HBAR or USDC, but only within daily limits and per-transaction limits, which are enforced by smart contracts

In the experiment, after the agent requested a data endpoint and the server returned a 402 challenge, the agent autonomously signed a micropayment transaction of 0.05 USDC on the Base L2 network and then obtained the data.

The gas fee for a single USDC transfer on Base is typically less than $0.01.

In this token issuance design, gas fees are paid exclusively in USDC with no pre-deposited collateral required, and the number of tokens held by the issuer is zero (no reserve, no team allocation).

The poster's marketplace interface manifest uses x402-v2, the Base chain (eip155:8453), USDC, a payTo address, with a listing fee of 0.01.

The programmability of stablecoins such as USDC allows for atomic payments, binding service delivery and payment settlement into the same on-chain transaction.

USDC is a stablecoin issued by Circle that is pegged 1:1 to the US dollar and runs on multiple blockchains including Ethereum and Solana.