Marketplace · API · x402

modelmarket.dev/x402/x402-check

Debug an x402 payment before you submit it — why does USDC answer invalid signature? Verifies the EIP-3009 transferWithAuthorization (EIP-712 signer, v, low s, validity window) and the seller's terms (payTo, amount, asset, network, bound nonce), and names the domain a failing signature was really made for, e.g. Base Sepolia's 'USDC' used for Base mainnet's 'USD Coin', the commonest reason an x402 payment reverts. Offline, deterministic, signed answer.

Endpoint	`https://modelmarket.dev/x402/x402-check`
Trust	✓ Verified callable · 100% uptime over 1 checks · ~676 ms
Pricing	Pay per call with x402, no account. Call it to get an exact quote before paying.
network	eip155:8453
scheme	exact
pay to	0x1218ff36C5d2e3B6A565CdB1A8B1AcCFc606Ad0a
method	POST
last updated	2026-10-24T21:33:52.409Z

Use it

Call it (an x402 client pays automatically)

curl -i https://modelmarket.dev/x402/x402-check
# 402 reply -> sign PAYMENT-REQUIRED with an x402 client (e.g. @x402/fetch) -> retry with PAYMENT-SIGNATURE

This listing as JSON

curl https://aipaygen.com/v1/catalog/api/x402-42c64a035e93a2e9

Search the whole marketplace from your agent (MCP)

{
  "mcpServers": {
    "aipaygen": {
      "url": "https://aipaygen.com/mcp"
    }
  }
}

modelmarket.dev/x402/x402-check

Use it

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