Open APIs V2

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Get Supported Configurations (V2)

Code
POST /papi/v2/b402/supported

Returns all payment kinds, extensions, and facilitator signer addresses supported by B402, conforming to the x402 v2 specification.

Differences from V1 (/papi/v1/b402/supported):

V1	V2
kinds[].x402Version: 1	kinds[].x402Version: 2
kinds[].scheme: "exact" for all methods	"exact" for eip3009 / permit2-exact, "upto" for permit2-upto
kinds[].extra.facilitatorAddress (overloaded: EOA for eip3009, proxy contract for permit2)	removed. Replaced by extra.signerAddress (EOA) + extra.spenderAddress (proxy, null for eip3009)
signers keys per-chain ("eip155:56")	signers keys are CAIP-2 wildcard namespaces ("eip155:*")

Request Body

No request body required. Send empty JSON {} or omit the body entirely.

Example

Code
{}

Code
curl -X POST https://{domain}/papi/v2/b402/supported \
-H 'Content-Type: application/json' \
-H 'X-Tesla-ClientId: {your client id}' \
-H 'X-Tesla-SignAccessToken: {your access token}' \
-H 'X-Tesla-Timestamp: {now}' \
-H 'X-Tesla-Signature: {signature}' \
-d '{}'

Response Body

Field	Type	Remarks
kinds	array	List of supported payment kinds
kinds[].x402Version	integer	x402 protocol version (always 2)
kinds[].scheme	string	"exact" for eip3009 / permit2-exact; "upto" for permit2-upto
kinds[].network	string	CAIP-2 network identifier (e.g. "eip155:56")
kinds[].extra	object	Scheme-specific details
kinds[].extra.name	string	EIP-712 domain name of the token (e.g. "U", "USD1", "USD Coin", "Tether USD")
kinds[].extra.version	string	EIP-712 domain version of the token contract
kinds[].extra.assetTransferMethod	string	"eip3009", "permit2-exact", or "permit2-upto" (b402 inline extension)
kinds[].extra.signerAddress	string	Facilitator EOA that signs on-chain transactions. Present for all methods.
kinds[].extra.spenderAddress	string	Spender contract (Permit2 proxy) address. Null for eip3009; required for permit2 signing.
extensions	array	Supported x402 extensions (currently empty [])
signers	map	CAIP-2 wildcard namespace → list of Facilitator signer (EOA) addresses

Example

Code
{
  "code": "000000",
  "message": "success",
  "data": {
    "kinds": [
      {
        "x402Version": 2,
        "scheme": "exact",
        "network": "eip155:56",
        "extra": {
          "name": "U",
          "version": "1",
          "assetTransferMethod": "eip3009",
          "signerAddress": "0x1111111111111111111111111111111111111111"
        }
      },
      {
        "x402Version": 2,
        "scheme": "exact",
        "network": "eip155:56",
        "extra": {
          "name": "U",
          "version": "1",
          "assetTransferMethod": "permit2-exact",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x2222222222222222222222222222222222222222"
        }
      },
      {
        "x402Version": 2,
        "scheme": "upto",
        "network": "eip155:56",
        "extra": {
          "name": "U",
          "version": "1",
          "assetTransferMethod": "permit2-upto",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x3333333333333333333333333333333333333333"
        }
      },
      {
        "x402Version": 2,
        "scheme": "exact",
        "network": "eip155:56",
        "extra": {
          "name": "USD1",
          "version": "1",
          "assetTransferMethod": "eip3009",
          "signerAddress": "0x1111111111111111111111111111111111111111"
        }
      },
      {
        "x402Version": 2,
        "scheme": "exact",
        "network": "eip155:56",
        "extra": {
          "name": "USD1",
          "version": "1",
          "assetTransferMethod": "permit2-exact",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x2222222222222222222222222222222222222222"
        }
      },
      {
        "x402Version": 2,
        "scheme": "upto",
        "network": "eip155:56",
        "extra": {
          "name": "USD1",
          "version": "1",
          "assetTransferMethod": "permit2-upto",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x3333333333333333333333333333333333333333"
        }
      },
      {
        "x402Version": 2,
        "scheme": "exact",
        "network": "eip155:56",
        "extra": {
          "name": "Tether USD",
          "version": "1",
          "assetTransferMethod": "permit2-exact",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x2222222222222222222222222222222222222222"
        }
      },
      {
        "x402Version": 2,
        "scheme": "upto",
        "network": "eip155:56",
        "extra": {
          "name": "Tether USD",
          "version": "1",
          "assetTransferMethod": "permit2-upto",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x3333333333333333333333333333333333333333"
        }
      },
      {
        "x402Version": 2,
        "scheme": "exact",
        "network": "eip155:56",
        "extra": {
          "name": "USD Coin",
          "version": "2",
          "assetTransferMethod": "permit2-exact",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x2222222222222222222222222222222222222222"
        }
      },
      {
        "x402Version": 2,
        "scheme": "upto",
        "network": "eip155:56",
        "extra": {
          "name": "USD Coin",
          "version": "2",
          "assetTransferMethod": "permit2-upto",
          "signerAddress": "0x1111111111111111111111111111111111111111",
          "spenderAddress": "0x3333333333333333333333333333333333333333"
        }
      }
    ],
    "extensions": [],
    "signers": {
      "eip155:*": ["0x1111111111111111111111111111111111111111"]
    }
  }
}

Notes:

• The response changes infrequently. It is safe to cache the result and refresh periodically (e.g. once per hour).
• signerAddress is the Facilitator externally-owned account (EOA) — the wallet that submits on-chain transactions and pays gas. Use it to recover/verify transaction origin.
• spenderAddress is the Permit2 proxy contract that the buyer authorises in their Permit2 signature (permit2Authorization.spender). It is absent (null, omitted from JSON) for eip3009 because EIP-3009 transfers are submitted directly against the token contract without a proxy.
• For permit2-upto, scheme is "upto" per the x402 v2 spec — the authorised amount is an upper bound, and the actual settled amount is specified at /settle time via settleAmount.
• signers keys use the CAIP-2 wildcard namespace (e.g. "eip155:*") rather than per-chain identifiers, matching the x402 v2 reference implementation. A single Facilitator EOA signs across all EVM chains in this namespace.

Forwarding Addresses to Buyers (Merchant Responsibility)

⚠️ Required: The merchant MUST forward signerAddress and spenderAddress from the /supported response into the paymentRequirements.extra object of the HTTP 402 Payment Required response returned to buyers. Buyers rely on these fields to construct a valid Permit2 signature — they cannot, and should not, call /supported themselves (the endpoint is gated by merchant credentials and is not part of the buyer-facing surface).

Per the x402 protocol, buyers never talk to B402 directly; the only channel between buyer and facilitator is the merchant's 402 response. If these fields are missing from the 402 body, the buyer has no way to know:

• Which contract to set as permit2Authorization.spender when signing (← spenderAddress).
• Which address to bind in witness.facilitator for permit2-upto signatures (← signerAddress).

Omitting them will cause buyer-side signing to fail, or produce signatures that B402 rejects at /verify with invalid_payload.

Field mapping: /supported response → merchant 402 response

From /supported response	Must appear in merchant's 402 response as	Required for
kinds[].extra.signerAddress	paymentRequirements.extra.signerAddress	All methods. Buyers bind it into witness.facilitator for permit2-upto signatures.
kinds[].extra.spenderAddress	paymentRequirements.extra.spenderAddress	permit2-exact and permit2-upto. Omit (or set to null) for eip3009.
kinds[].extra.name	paymentRequirements.extra.name	All methods — EIP-712 domain name used by buyer when building the typed data.
kinds[].extra.version	paymentRequirements.extra.version	All methods — EIP-712 domain version used by buyer when building the typed data.
kinds[].extra.assetTransferMethod	paymentRequirements.extra.assetTransferMethod	All methods — selects which signing scheme the buyer must use.

Example — merchant 402 response body (permit2-upto)

Code
HTTP/1.1 402 Payment Required
Content-Type: application/json

{
  "x402Version": 2,
  "accepts": [
    {
      "scheme": "upto",
      "network": "eip155:56",
      "amount": "100000000",
      "asset": "0x55d398326f99059ff775485246999027b3197955",
      "payTo": "0x8B3a350e2f3E6B9cC6FB10Fd106bA08f08bec5D2",
      "maxTimeoutSeconds": 300,
      "extra": {
        "name": "Tether USD",
        "version": "1",
        "assetTransferMethod": "permit2-upto",
        "signerAddress": "0x1111111111111111111111111111111111111111",
        "spenderAddress": "0x3333333333333333333333333333333333333333"
      }
    }
  ]
}

Implementation tip: Cache the /supported response on the merchant side (see note above) and copy signerAddress / spenderAddress / name / version / assetTransferMethod from the matching kinds[] entry into every 402 response you emit. Do not hardcode these addresses — they may change when B402 upgrades Permit2 proxies, and /supported is the single source of truth.