Skip to main content

​
Multi-chain Settlement

The gateway settles paid calls in USDC over x402 on multiple networks. A paid endpoint’s 402 response lists one payment requirement per network the API is configured for; the buyer picks a network, pays on it, and the publisher is paid out on that same network.

​
Supported networks

Networknetwork idUSDC assetStatus
Basebase0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913Live
SolanasolanaEPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1vLive
Polygonpolygon0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359Coming soon
Arbitrumarbitrum0xaf88d065e77c8cC2239327C5EDb3A432268e5831Coming soon
Polygon and Arbitrum are enabled as facilitator support lands. The currently enabled set is published live in meta.settlement.networks of the discovery document at https://gateway.apiosk.com/.well-known/x402, which also lists the per-resource accepts entries with their networks.

​
The multi-accept 402

A paid route’s 402 now carries multiple accepts[] entries, one per network the API is configured for:
  • the publisher’s primary network comes first
  • Base is always included as a fallback
  • any additionally configured chains follow
Every entry prices the same resource at the same USDC amount; only network, asset, payTo, and extra differ. Solana entries carry extra.feePayer (the facilitator’s fee payer) instead of the EVM EIP-712 extra.{name,version}. 
{
  "error": "Payment required",
  "accepts": [
    {
      "scheme": "exact",
      "network": "base",
      "maxAmountRequired": "60000",
      "resource": "https://gateway.apiosk.com/weather/current",
      "description": "Current weather conditions",
      "mimeType": "application/json",
      "payTo": "0x8f3C1a9bF2d47e05A6b21C9d8E4f70b3D5a6E210",
      "maxTimeoutSeconds": 60,
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "extra": { "name": "USDC", "version": "2" }
    },
    {
      "scheme": "exact",
      "network": "solana",
      "maxAmountRequired": "60000",
      "resource": "https://gateway.apiosk.com/weather/current",
      "description": "Current weather conditions",
      "mimeType": "application/json",
      "payTo": "7sPjV9dQzR4mK2xW8yBtF5cN1aHgU6eLoJpTq3ZvMnED",
      "maxTimeoutSeconds": 60,
      "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
      "extra": { "feePayer": "FaciL1tatorFeePayerPubkey11111111111111111111" }
    }
  ],
  "x402Version": 1
}

​
How buyers choose a network

  1. Read the accepts[] array from the 402.
  2. Pick the entry whose network you can pay on.
  3. Sign and pay per that entry (EVM entries via the EIP-712 domain in extra, Solana entries via the facilitator fee payer in extra.feePayer).
  4. Put the network name (base, solana, polygon, arbitrum) in the payment payload you send in x-payment: the gateway settles against the matching accepts entry.
The price is identical on every entry, so the choice is purely about which chain your payer holds USDC on.

​
Publisher payout wallets

Publishers configure settlement networks by attaching payout wallets in the provider portal:
  • attach up to 4 payout wallets per API: exactly one per chain, chosen from your verified wallets
  • the connected wallet’s chain is auto-detected: Base, Polygon, and Arbitrum via the wallet’s active chain; Solana via Phantom
  • wallet ownership must be verified before a wallet can be attached: EVM wallets sign the ownership message with an EIP-191 signature, Solana wallets sign the same message with Phantom (ed25519)

​
Payout routing

Earnings settle to the wallet of the chain the buyer paid on: pay on Solana, and the publisher’s Solana wallet receives the payout; pay on Base, and the Base wallet does. The split is unchanged, 98% to the publisher, 2% platform fee, on every network.

​
Base fallback guarantee

If a network is unavailable, facilitator support is missing or the listing’s configuration for that chain is incomplete, the gateway falls back to Base USDC. Because every 402 always includes a Base entry, a 402 is always payable.
The SEPA Direct Debit rail is unaffected by network selection, it settles in euros on the bank side regardless of which chains a listing is configured for. See Payment Options.