HTTP API — One-time Payment#

This page is the API reference for one-time payment, covering the full interface definitions for both exact and charge schemes. For usage guides and SDK integration examples, see One-time payment · Integration docs.

`exact` or `charge`?#

exact — single recipient, supports both sync and async settlement.

charge — supports a single recipient too, plus splits, i.e. one payment to multiple addresses (≤10). Defaults to and only supports sync settlement.

Dimension	`exact`	`charge`
Recipient	Single	Single / one-payment-to-multiple-addresses (≤10)
Settlement timing	Sync / async	Default and sync only
Integration guide	`exact` path	`charge` path

Base URL: https://web3.okx.com
exact path prefix: /api/v6/pay/x402
charge path prefix: /api/v6/pay/mpp/charge
Network: X Layer (chainId 196, CAIP-2 identifier eip155:196)

Authentication#

All endpoints require API Key authentication. The following headers must be provided:

Header	Required	Description
`OK-ACCESS-KEY`	Yes	API Key
`OK-ACCESS-SIGN`	Yes	Request signature
`OK-ACCESS-PASSPHRASE`	Yes	API passphrase
`OK-ACCESS-TIMESTAMP`	Yes	ISO 8601 timestamp
`Content-Type`	Yes	`application/json` for POST requests

All responses use a unified envelope:

json

{
  "code": "0",
  "msg": "success",
  "data": { /* business fields */ }
}

On business errors, code is non-"0" and data is null. See the Error codes section at the end of this page.

`exact` Scheme#

1. /api/v6/pay/x402/supported#

GET

/api/v6/pay/x402/supported

Query the schemes, networks, and signers supported by the Broker. The Seller SDK calls this endpoint to construct the accepts array of the 402 response.

Request parameters#

None.

Response parameters#

Parameter	Type	Description
`kinds`	`Array<SupportedKind>`	Supported payment-type list
`kinds[].x402Version`	`Integer`	Protocol version, e.g. `2`
`kinds[].scheme`	`String`	Settlement scheme: `exact` / `aggr_deferred`
`kinds[].network`	`String`	CAIP-2 network identifier, e.g. `eip155:196`
`kinds[].extra`	`Object`	Scheme-specific extension config
`extensions`	`Array<String>`	Supported extension identifiers
`signers`	`Object`	CAIP-2 wildcard → array of signer addresses

Request example#

bash

curl --location --request GET 'https://web3.okx.com/api/v6/pay/x402/supported' \
--header 'OK-ACCESS-KEY: 37c541a1-****-****-****-10fe7a038418' \
--header 'OK-ACCESS-SIGN: leaV********3uw=' \
--header 'OK-ACCESS-PASSPHRASE: 1****6' \
--header 'OK-ACCESS-TIMESTAMP: 2023-10-18T12:21:41.274Z'

Response example#

json

{
  "code": "0",
  "msg": "",
  "data": {
    "kinds": [
      { "x402Version": 2, "scheme": "exact",         "network": "eip155:196", "extra": null },
      { "x402Version": 2, "scheme": "aggr_deferred", "network": "eip155:196", "extra": null }
    ],
    "extensions": [],
    "signers": {
      "eip155:*": ["0x...brokerSignerAddress"]
    }
  }
}

2. /api/v6/pay/x402/verify#

POST

/api/v6/pay/x402/verify

Validate the Buyer's signed payment authorization. No on-chain transaction is executed.

Request parameters#

Parameter	Type	Required	Description
`x402Version`	`Integer`	Yes	Protocol version, e.g. `2`
`paymentPayload`	`Object`	Yes	The payment payload the client sends with the protected request. See PaymentPayload
`paymentRequirements`	`Object`	Yes	The Seller-defined payment requirements. See PaymentRequirements

Constraint: paymentPayload.accepted.scheme and paymentRequirements.scheme must both be "exact".

Response parameters#

Parameter	Type	Description
`isValid`	`Boolean`	`true` = passed, `false` = failed
`invalidReason`	`String`	Machine-readable invalid reason (returned on failure)
`invalidMessage`	`String`	Human-readable invalid message (returned on failure)
`payer`	`String`	Payer wallet address

Request example#

bash

curl --location --request POST 'https://web3.okx.com/api/v6/pay/x402/verify' \
--header 'Content-Type: application/json' \
--header 'OK-ACCESS-KEY: 37c541a1-****-****-****-10fe7a038418' \
--header 'OK-ACCESS-SIGN: leaV********3uw=' \
--header 'OK-ACCESS-PASSPHRASE: 1****6' \
--header 'OK-ACCESS-TIMESTAMP: 2023-10-18T12:21:41.274Z' \
--data '{
  "x402Version": 2,
  "paymentPayload": {
    "x402Version": 2,
    "resource": {
      "url": "https://api.example.com/premium-data",
      "description": "Access to premium data",
      "mimeType": "application/json"
    },
    "accepted": {
      "scheme": "exact",
      "network": "eip155:196",
      "amount": "10000",
      "asset": "0x4ae46a509f6b1d9056937ba4500cb143933d2dc8",
      "payTo": "0xRecipientAddress",
      "maxTimeoutSeconds": 60,
      "extra": { "name": "USDG", "version": "2" }
    },
    "payload": {
      "signature": "0xf3746613c2d920b5fdabc0856f2aeb2d4f88ee6037b8cc5d04a71a4462f13480...",
      "authorization": {
        "from": "0x742d35Cc6634C0532925a3b844Bc454e4438f44e",
        "to": "0xRecipientAddress",
        "value": "10000",
        "validAfter": "0",
        "validBefore": "1740672154",
        "nonce": "0xf374661..."
      }
    }
  },
  "paymentRequirements": {
    "scheme": "exact",
    "network": "eip155:196",
    "amount": "10000",
    "asset": "0x4ae46a509f6b1d9056937ba4500cb143933d2dc8",
    "payTo": "0xRecipientAddress",
    "maxTimeoutSeconds": 60,
    "extra": { "name": "USDG", "version": "2" }
  }
}'

Response example — verification passed#

json

{
  "code": "0",
  "msg": "success",
  "data": {
    "isValid": true,
    "invalidReason": null,
    "invalidMessage": null,
    "payer": "0xcb30ed083ad246b126a3aa1f414b44346e83e67d"
  }
}

Response example — verification failed#

json

{
  "code": "0",
  "msg": "success",
  "data": {
    "isValid": false,
    "invalidReason": "insufficient_funds",
    "invalidMessage": "Payer balance is below required amount",
    "payer": "0xcb30ed083ad246b126a3aa1f414b44346e83e67d"
  }
}

3. /api/v6/pay/x402/settle#

POST

/api/v6/pay/x402/settle

After verification passes, submit the on-chain settlement. In exact mode, each call initiates an independent on-chain transferWithAuthorization transaction.

Request parameters#

Parameter	Type	Required	Description
`x402Version`	`Integer`	Yes	Protocol version, e.g. `2`
`paymentPayload`	`Object`	Yes	Same as verify
`paymentRequirements`	`Object`	Yes	Same as verify
`syncSettle`	`Boolean`	No	OKX extension. `true` = wait for on-chain confirmation; `false` (default) = async broadcast

Response parameters#

Parameter	Type	Description
`success`	`Boolean`	Whether settlement succeeded
`errorReason`	`String`	Machine-readable failure reason (returned on failure)
`errorMessage`	`String`	Human-readable failure message (returned on failure)
`payer`	`String`	Payer wallet address
`transaction`	`String`	On-chain transaction hash
`network`	`String`	CAIP-2 network identifier
`status`	`String`	OKX extension. Settlement status — see table below

status values:

`syncSettle`	Result	`status`	`transaction`
`false` (default)	Broadcast	`pending`	txHash
`true`	Confirmed on-chain	`success`	txHash
`true`	Wait timeout	`timeout`	txHash
—	Verify / simulation / on-chain failure	`""`	`""`

Request example#

bash

curl --location --request POST 'https://web3.okx.com/api/v6/pay/x402/settle' \
--header 'Content-Type: application/json' \
--header 'OK-ACCESS-KEY: 37c541a1-****-****-****-10fe7a038418' \
--header 'OK-ACCESS-SIGN: leaV********3uw=' \
--header 'OK-ACCESS-PASSPHRASE: 1****6' \
--header 'OK-ACCESS-TIMESTAMP: 2023-10-18T12:21:41.274Z' \
--data '{
  "x402Version": 2,
  "paymentPayload": { "...same as verify..." },
  "paymentRequirements": { "...same as verify..." },
  "syncSettle": true
}'

Response example — sync settle success (syncSettle=true)#

json

{
  "code": "0",
  "msg": "success",
  "data": {
    "success": true,
    "errorReason": null,
    "errorMessage": null,
    "payer": "0xcb30ed083ad246b126a3aa1f414b44346e83e67d",
    "transaction": "0x4f46ed8eac92ddbccfb56a88ff827db3616c7beb191adabbeeded901340bd7d5",
    "network": "eip155:196",
    "status": "success"
  }
}

Response example — async settle (syncSettle=false)#

json

{
  "code": "0",
  "msg": "success",
  "data": {
    "success": true,
    "errorReason": null,
    "errorMessage": null,
    "payer": "0xcb30ed083ad246b126a3aa1f414b44346e83e67d",
    "transaction": "0x4f46ed8eac92ddbccfb56a88ff827db3616c7beb191adabbeeded901340bd7d5",
    "network": "eip155:196",
    "status": "pending"
  }
}

Response example — settle failure#

json

{
  "code": "0",
  "msg": "success",
  "data": {
    "success": false,
    "errorReason": "insufficient_funds",
    "errorMessage": "Transaction reverted",
    "payer": "0xcb30ed083ad246b126a3aa1f414b44346e83e67d",
    "transaction": "",
    "network": "eip155:196",
    "status": ""
  }
}

4. /api/v6/pay/x402/settle/status#

GET

/api/v6/pay/x402/settle/status

Query settlement status by on-chain transaction hash — used for polling in async settlement (syncSettle=false).

Request parameters#

Parameter	Location	Type	Required	Description
`txHash`	query	`String`	Yes	On-chain transaction hash

Response parameters#

Parameter	Type	Description
`success`	`Boolean`	Whether the query succeeded (`false` if `txHash` not found)
`errorReason`	`String`	Machine-readable failure reason
`errorMessage`	`String`	Human-readable failure message
`payer`	`String`	Payer wallet address
`transaction`	`String`	On-chain transaction hash
`network`	`String`	CAIP-2 network identifier
`status`	`String`	Current settlement status: `pending` / `success` / `failed`

Request example#

bash

curl --location --request GET 'https://web3.okx.com/api/v6/pay/x402/settle/status?txHash=0x4f46ed8eac92ddbccfb56a88ff827db3616c7beb191adabbeeded901340bd7d5' \
--header 'OK-ACCESS-KEY: 37c541a1-****-****-****-10fe7a038418' \
--header 'OK-ACCESS-SIGN: leaV********3uw=' \
--header 'OK-ACCESS-PASSPHRASE: 1****6' \
--header 'OK-ACCESS-TIMESTAMP: 2023-10-18T12:21:41.274Z'

Response example — query success#

json

{
  "code": "0",
  "msg": "success",
  "data": {
    "success": true,
    "errorReason": null,
    "errorMessage": null,
    "payer": "0xcb30ed083ad246b126a3aa1f414b44346e83e67d",
    "transaction": "0x4f46ed8eac92ddbccfb56a88ff827db3616c7beb191adabbeeded901340bd7d5",
    "network": "eip155:196",
    "status": "success"
  }
}

Response example — transaction not found#

json

{
  "code": "0",
  "msg": "success",
  "data": {
    "success": false,
    "errorReason": "not_found",
    "errorMessage": "Transaction not found for txHash: 0xabc123...",
    "payer": null,
    "transaction": null,
    "network": null,
    "status": null
  }
}

`charge` Scheme#

charge provides one-time token transfer based on an HTTP 402 Challenge-Credential flow.

Server-side payment (transaction mode): the Buyer signs an EIP-3009 authorization, and the Broker submits the on-chain transaction on their behalf
Client-side payment (hash mode): the Buyer broadcasts the on-chain transaction themselves, and the Broker verifies its validity

5. /api/v6/pay/mpp/charge/settle#

POST

/api/v6/pay/mpp/charge/settle

Server-side payment — submit the on-chain ERC-20 transfer on behalf of the user. Supports the EIP-3009 authorization scheme and splits (up to 10).

Request parameters#

Parameter	Type	Required	Description
`challenge`	`Object`	Yes	The Challenge object issued by the server (echo back as-is). See Challenge
`payload`	`Object`	Yes	EVM payment receipt
`payload.type`	`String`	Yes	Always `"transaction"`
`payload.authorization`	`Object`	Yes	EIP-3009 authorization object
`payload.authorization.type`	`String`	Yes	Always `"eip-3009"`
`payload.authorization.from`	`String`	Yes	Payer wallet address
`payload.authorization.to`	`String`	Yes	Recipient wallet address
`payload.authorization.value`	`String`	Yes	Payment amount (base units)
`payload.authorization.validAfter`	`String`	Yes	Authorization start Unix timestamp
`payload.authorization.validBefore`	`String`	Yes	Authorization expiry Unix timestamp
`payload.authorization.nonce`	`String`	Yes	Random bytes32, unique per authorization
`payload.authorization.signature`	`String`	Yes	65-byte EIP-712 signature (r‖s‖v)
`payload.authorization.splits`	`Array`	No	Splits list (max 10). See Split
`source`	`String`	No	Payer DID (`did:pkh:eip155:196:0x...`)

Response parameters#

Parameter	Type	Description
`method`	`String`	Always `"evm"`
`reference`	`String`	On-chain transaction hash (0x-prefixed)
`status`	`String`	Always `"success"`
`timestamp`	`String`	RFC 3339 settlement time
`chainId`	`Integer`	Settlement chain ID, e.g. `196`
`challengeId`	`String`	Challenge ID, for client correlation
`externalId`	`String`	Echoed merchant order ID from the Challenge request

Request example#

bash

curl --location --request POST 'https://web3.okx.com/api/v6/pay/mpp/charge/settle' \
--header 'Content-Type: application/json' \
--header 'OK-ACCESS-KEY: 37c541a1-****-****-****-10fe7a038418' \
--header 'OK-ACCESS-SIGN: leaV********3uw=' \
--header 'OK-ACCESS-PASSPHRASE: 1****6' \
--header 'OK-ACCESS-TIMESTAMP: 2023-10-18T12:21:41.274Z' \
--data '{
  "challenge": {
    "id": "qB3wErTyU7iOpAsD9fGhJk",
    "realm": "api.example.com",
    "method": "evm",
    "intent": "charge",
    "request": "eyJhbW91bnQiOiIxMDAwMCIsImN1cnJlbmN5Ijoi...",
    "expires": "2026-04-01T12:05:00Z"
  },
  "payload": {
    "type": "transaction",
    "authorization": {
      "type": "eip-3009",
      "from": "0x1234567890abcdef1234567890abcdef12345678",
      "to": "0x742d35Cc6634c0532925a3b844bC9e7595F8fE00",
      "value": "10000",
      "validAfter": "0",
      "validBefore": "9999999999",
      "nonce": "0x9337d07c707c703b86f05e66b9097e38e7587e7ecfe740551ac608693864abdd",
      "signature": "0x5a9827232b5c640d7239462dbb3f0eede1aa2522eb53e552369db8db66720293..."
    }
  }
}'

Response example#

json

{
  "code": "0",
  "msg": "",
  "data": {
    "method": "evm",
    "reference": "0xabcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890",
    "status": "success",
    "timestamp": "2026-04-01T12:04:30Z",
    "chainId": 196,
    "challengeId": "qB3wErTyU7iOpAsD9fGhJk",
    "externalId": "order-12345"
  }
}

Request example — with splits#

bash

curl --location --request POST 'https://web3.okx.com/api/v6/pay/mpp/charge/settle' \
--header 'Content-Type: application/json' \
--header 'OK-ACCESS-KEY: 37c541a1-****-****-****-10fe7a038418' \
--header 'OK-ACCESS-SIGN: leaV********3uw=' \
--header 'OK-ACCESS-PASSPHRASE: 1****6' \
--header 'OK-ACCESS-TIMESTAMP: 2023-10-18T12:21:41.274Z' \
--data '{
  "challenge": {
    "id": "sP1itPaym3ntEx4mple",
    "realm": "marketplace.example.com",
    "method": "evm",
    "intent": "charge",
    "request": "eyJ...",
    "expires": "2026-04-01T12:05:00Z"
  },
  "payload": {
    "type": "transaction",
    "authorization": {
      "type": "eip-3009",
      "from": "0x1234567890abcdef1234567890abcdef12345678",
      "to": "0x742d35Cc6634c0532925a3b844bC9e7595F8fE00",
      "value": "940000",
      "validAfter": "0",
      "validBefore": "1775059500",
      "nonce": "0x1111111111111111111111111111111111111111111111111111111111111111",
      "signature": "0xabc...primary",
      "splits": [
        {
          "from": "0x1234567890abcdef1234567890abcdef12345678",
          "to": "0xA1B2C3d4e5F6a1B2c3d4e5F6a1b2c3d4e5F6a1b2",
          "value": "50000",
          "validAfter": "0",
          "validBefore": "1775059500",
          "nonce": "0x2222222222222222222222222222222222222222222222222222222222222222",
          "signature": "0xdef...split1"
        },
        {
          "from": "0x1234567890abcdef1234567890abcdef12345678",
          "to": "0xC4D5e6F7A8B9c4D5E6f7a8B9c4d5e6F7a8b9C4D5",
          "value": "10000",
          "validAfter": "0",
          "validBefore": "1775059500",
          "nonce": "0x3333333333333333333333333333333333333333333333333333333333333333",
          "signature": "0xghi...split2"
        }
      ]
    }
  },
  "source": "did:pkh:eip155:196:0x1234567890abcdef1234567890abcdef12345678"
}'

6. /api/v6/pay/mpp/charge/verifyHash#

POST

/api/v6/pay/mpp/charge/verifyHash

Client-side payment — verify that the on-chain transaction broadcast by the client matches the payment requirements in the Challenge.

Request parameters#

Parameter	Type	Required	Description
`challenge`	`Object`	Yes	The Challenge object issued by the server (echo back as-is). See Challenge
`payload`	`Object`	Yes	Payment receipt
`payload.type`	`String`	Yes	Always `"hash"`
`payload.hash`	`String`	Yes	The on-chain transaction hash already broadcast by the client
`source`	`String`	Yes	Payer DID (`did:pkh:eip155:196:0x...`)

Response parameters#

Parameter	Type	Description
`method`	`String`	Always `"evm"`
`reference`	`String`	On-chain transaction hash (0x-prefixed)
`status`	`String`	Always `"success"`
`timestamp`	`String`	RFC 3339 confirmation time
`chainId`	`Integer`	Chain ID, e.g. `196`
`challengeId`	`String`	Challenge ID, for client correlation
`externalId`	`String`	Echoed merchant order ID from the Challenge request

Request example#

bash

curl --location --request POST 'https://web3.okx.com/api/v6/pay/mpp/charge/verifyHash' \
--header 'Content-Type: application/json' \
--header 'OK-ACCESS-KEY: 37c541a1-****-****-****-10fe7a038418' \
--header 'OK-ACCESS-SIGN: leaV********3uw=' \
--header 'OK-ACCESS-PASSPHRASE: 1****6' \
--header 'OK-ACCESS-TIMESTAMP: 2023-10-18T12:21:41.274Z' \
--data '{
  "challenge": {
    "id": "qB3wErTyU7iOpAsD9fGhJk",
    "realm": "api.example.com",
    "method": "evm",
    "intent": "charge",
    "request": "eyJhbW91bnQiOiIxMDAwMCIsImN1cnJlbmN5Ijoi...",
    "expires": "2026-04-01T12:05:00Z"
  },
  "payload": {
    "type": "hash",
    "hash": "0xd9a703784f0cb489ea90c52f5626a22516f39c5063558733bb742972fdf6f722"
  },
  "source": "did:pkh:eip155:196:0x1234567890abcdef1234567890abcdef12345678"
}'

Response example#

json

{
  "code": "0",
  "msg": "",
  "data": {
    "method": "evm",
    "reference": "0x9f8e7d6c5b4a3928170fabcdef1234567890abcdef1234567890abcdef123456",
    "status": "success",
    "timestamp": "2026-04-01T12:04:30Z",
    "chainId": 196,
    "challengeId": "qB3wErTyU7iOpAsD9fGhJk",
    "externalId": "order-12345"
  }
}

Common data structures#

PaymentPayload#

After signing, the Buyer passes this through the X-PAYMENT header (base64-encoded) to the Seller, who forwards it as-is to the Broker.

Parameter	Type	Required	Description
`x402Version`	`Integer`	Yes	Protocol version, e.g. `2`
`resource`	`Object`	No	Protected-resource description
`resource.url`	`String`	Yes	The URL of the protected resource
`resource.description`	`String`	No	Resource description
`resource.mimeType`	`String`	No	Expected response MIME type
`accepted`	`Object`	Yes	The payment option chosen by the Buyer (selected from the `accepts` array). Same shape as PaymentRequirements
`payload`	`Object`	Yes	Signed data
`payload.signature`	`String`	Yes	EIP-712 signature (EOA signature)
`payload.authorization`	`Object`	Yes	EIP-3009 authorization parameters. See Authorization

PaymentRequirements#

Used both as an entry of the 402 response accepts array and as paymentPayload.accepted.

Parameter	Type	Required	Description
`scheme`	`String`	Yes	Always `"exact"`
`network`	`String`	Yes	CAIP-2 network identifier, e.g. `eip155:196`
`amount`	`String`	Yes	Payment amount (atomic-unit string)
`asset`	`String`	Yes	Token contract address
`payTo`	`String`	Yes	Recipient wallet address
`maxTimeoutSeconds`	`Integer`	No	Max payment-completion timeout (seconds)
`extra`	`Object`	No	Scheme-specific extension (e.g. `name` / `version`)

Authorization#

Parameter	Type	Required	Description
`from`	`String`	Yes	Payer wallet address (EOA)
`to`	`String`	Yes	Recipient wallet address (must equal `payTo`)
`value`	`String`	Yes	Payment amount (atomic units, must equal `amount`)
`validAfter`	`String`	Yes	Authorization start Unix timestamp
`validBefore`	`String`	Yes	Authorization expiry Unix timestamp
`nonce`	`String`	Yes	32-byte random nonce (0x hex, anti-replay)

Challenge#

The Challenge object issued by the server, echoed back by the client as-is.

Parameter	Type	Required	Description
`id`	`String`	Yes	Challenge ID
`realm`	`String`	Yes	Protection space identifier
`method`	`String`	Yes	Always `"evm"`
`intent`	`String`	Yes	Payment intent: `"charge"` / `"session"`
`request`	`String`	Yes	base64url-encoded request parameters
`expires`	`String`	Yes	Expiry time (ISO 8601)

Split#

A single split entry in the Charge splits list — each requires its own signature.

Parameter	Type	Required	Description
`from`	`String`	Yes	Payer address (same as primary signature)
`to`	`String`	Yes	Split recipient address
`value`	`String`	Yes	Split amount (base units)
`validAfter`	`String`	Yes	Authorization start Unix timestamp
`validBefore`	`String`	Yes	Authorization expiry Unix timestamp
`nonce`	`String`	Yes	Independent nonce (bytes32)
`signature`	`String`	Yes	65-byte EIP-712 signature

Supported networks and tokens#

Network	Chain Index	Status
X Layer	196	Supported

Stablecoins supported on X Layer:

Token	Contract address
USDG	`0x4ae46a509f6b1d9056937ba4500cb143933d2dc8`
USD₮0	`0x779ded0c9e1022225f8e0630b35a9b54be713736`

Error codes#

Error responses use the unified envelope {"code": "<code>", "msg": "<message>", "data": null}.

1. Authentication errors (HTTP 401)#

Code	Description
50103	Header `OK-ACCESS-KEY` cannot be empty
50104	Header `OK-ACCESS-PASSPHRASE` cannot be empty
50105	Header `OK-ACCESS-PASSPHRASE` is invalid
50106	Header `OK-ACCESS-SIGN` cannot be empty
50107	Header `OK-ACCESS-TIMESTAMP` cannot be empty
50111	Invalid `OK-ACCESS-KEY`
50112	Invalid `OK-ACCESS-TIMESTAMP`
50113	Invalid signature

2. Request errors#

Code	HTTP status	Description
50011	429	User request rate exceeds the per-endpoint limit
50014	400	Required parameter `{param}` cannot be empty

3. Business errors#

Code	HTTP status	Description
50026	500	System error, please retry later
81001	200	`{param}` parameter error
81004	200	Unsupported chain
80007	200	Risky address

4. verify / settle business fields#

For exact endpoints, failure reasons are returned in data.invalidReason (verify) or data.errorReason (settle / settle/status). Common values:

Field value	Applies to	Description
`insufficient_funds`	verify, settle	Payer balance insufficient
`nonce_already_used`	verify, settle	Nonce already used
`expired_authorization`	verify, settle	Authorization expired
`signature_invalid`	verify, settle	Signature verification failed
`requirements_mismatch`	verify, settle	`accepted` does not match `paymentRequirements`
`transaction_reverted`	settle	On-chain transaction reverted
`chain_unavailable`	settle	On-chain RPC unavailable
`not_found`	settle/status	`txHash` not found in Broker records

5. `charge` business errors#

Code	Name	Description
8000	SERVICE_ERROR	Internal API service error
70000	invalid_params	Missing required field or invalid format
70001	unsupported_chain	Chain not in supported list
70002	payer_blocked	Payer is blocklisted
70003	invalid_credential	source missing, or txHash already used
70004	invalid_signature	Signature verification failed
70005	split_sum_exceeds_total	Split total >= primary amount
70006	split_count_exceeded	Split count > 10
70007	tx_not_confirmed	Transaction not confirmed on-chain
70009	challenge_invalid	Challenge does not exist or has expired