Create x402 Sign

Create an ERC-3009 authorization signature via MPC

POST /api/v1/x402/sign

Create x402 sign

cURL

curl --request POST \
  --url https://api.paratro.com/api/v1/x402/sign \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "from_address": "0xbFa643c784f1DAB3169a856107c992Fb15f29912",
  "to_address": "0x379d92924fe31AAC58D039FfE60215fd3a2B773B",
  "chain": "base",
  "amount": "1.5",
  "valid_after": 0,
  "valid_before": 1774601102
}
'

200

{
  "tx_id": "<string>",
  "status": "PENDING",
  "eip712_hash": "<string>",
  "nonce": "<string>",
  "valid_after": 123,
  "valid_before": 123
}

Create x402 Sign

Request the platform to generate an ERC-3009 transferWithAuthorization signature using MPC threshold signing.

The system computes the EIP-712 typed data hash, locks the USDC balance, and dispatches the signing task to the TSS engine. The signing result is returned directly in the response.

from_address · string · required

Payer address (must belong to the authenticated client, max 128 characters).

to_address · string · required

Recipient address (max 128 characters).

chain · string · required

Enabled x402 signing chain configured in the gateway, for example base, base-sepolia, ethereum, or polygon.

amount · string · required

Amount in human-readable units (e.g., "1.5" for 1.5 USDC). For upto scheme, this is the maximum authorized amount.

scheme · string

Payment scheme: "exact" (default) or "upto". With exact, the payer authorizes a fixed amount. With upto, the payer authorizes a maximum amount and the actual settlement can be any amount up to this limit.

valid_after · integer

Unix timestamp (seconds) before which the authorization is not yet valid. Defaults to 0 (immediately effective). Must be less than valid_before.

valid_before · integer · required

Unix timestamp (seconds) after which the authorization expires. Must be greater than 0.

Response

{
  "tx_id": "7f9da3de-5899-43c6-8104-b96187df024f",
  "status": "PENDING",
  "eip712_hash": "0xabc123...",
  "nonce": "0xdef456...",
  "valid_after": 0,
  "valid_before": 1774601102
}

Field	Type	Description
tx_id	string	Unique transaction ID for polling
status	string	Initial status: PENDING
eip712_hash	string	EIP-712 typed data hash
nonce	string	Random nonce for the authorization (hex)
valid_after	integer	Unix timestamp echoed from the request
valid_before	integer	Expiration Unix timestamp

Errors

HTTP	Code	Condition
400	invalid_parameter	Invalid request body or missing required fields
400	insufficient_balance	Insufficient USDC balance
400	invalid_address	Address format invalid
400	wallet_not_active	Wallet is not in active state
404	not_found	No matching asset found for the address/chain
500	internal_error	Internal processing failure

Authorizations

Authorization · string · header · required

JWT access token obtained from the /api/v1/auth/token endpoint.

Body

application/json

from_address · string · required

Maximum string length: 128

to_address · string · required

Maximum string length: 128

chain · string · required

amount · string · required

valid_before · integer<int64> · required

valid_after · integer<int64> · default: 0

Response

200

application/json

Signing request accepted.

tx_id · string · required

status · string · required

Example:

"PENDING"

eip712_hash · string · required

nonce · string · required

valid_after · integer<int64> · required

valid_before · integer<int64> · required