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Payment

x402 Protocol

How Concierge uses HTTP 402 for machine-to-machine stablecoin payments.

Concierge does not issue API keys. Payment is the gate — agents and browsers pay per request using x402 v2, settled through PayAI (primary) with Dexter as fallback facilitator. Dexter settlements auto-list on OpenDexter. BNB USDT and USDC use Dexter Permit2 when X402_BNB_ENABLED=true.

Flow

402 + PAYMENT-REQUIRED

First POST without payment returns requirements (network, asset, amount, payee).

Sign transfer

Wallet or x402 client signs the transfer to the listed payTo address (BNB may require a one-time Permit2 approval).

PAYMENT-SIGNATURE retry

Repeat the request with header PAYMENT-SIGNATURE (base64 JSON payload).

200 + PAYMENT-RESPONSE

Server verifies and settles; response includes settlement metadata.

Supported chains

  • Base — USDC (configure X402_EVM_PAY_TO)
  • Arbitrum — USDC (same EVM pay-to; disable with X402_ARBITRUM_ENABLED=false)
  • Robinhood Chain — USDG via Primer (eip155:4663)
  • BNB Smart Chain — USDT or USDC via Dexter Permit2 (eip155:56, 18 decimals; enable with X402_BNB_ENABLED=true)
  • Solana — USDC via PayAI/Dexter (optional X402_SOL_PAY_TO)
  • Solana — native project tokens via Token Pay self-settle (one accept per live merchant; extra.settlement: "self")
  • TCX — Concierge default merchant; live when SOON_TOKEN_MINT is set (mint F2bnJW1z55UQ9ZqGX5RwYQfvNJrd23n66eyBV5QZpump)

Check accepts in the 402 body or GET /api/x402-config / GET /api/token-pay for enabled merchants. Beta partners register via Token Pay onboarding.

Headers

HeaderDirectionPurpose
PAYMENT-REQUIREDResponse (402)Payment requirements (base64 JSON)
PAYMENT-SIGNATURERequestSigned payment proof
PAYMENT-RESPONSEResponse (200)Settlement receipt

Marketplace probes

GET on paid routes also returns 402 so x402scan, MPPscan, and AgentCash can discover pricing without a body.

Verified registries: x402scan · MPPscan

Fan-out: /.well-known/x402 lists all paid resources. Bazaar extensions on 402 include input and output JSON schemas.

Quickstart Token Pay (beta) MPP & AgentCash Pricing

Concierge · Executive Lounge