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POST
/
v1
/
w3s
/
contracts
/
monitors
Create Event Monitor
curl --request POST \
  --url https://api.circle.com/v1/w3s/contracts/monitors \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "blockchain": "ETH",
  "contractAddress": "0x6bc50ff08414717f000431558c0b585332c2a53d",
  "eventSignature": "Transfer(address,address,uint256)",
  "idempotencyKey": "a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11"
}
'
{
  "data": {
    "eventMonitor": {
      "id": "e3c998a5-bdf1-4f3e-812f-24da238c0fff",
      "blockchain": "MATIC-AMOY",
      "contractAddress": "0x1e124d7384cd34448ea5907bd0052a79355ab5eb",
      "eventSignature": "Transfer(address indexed from, address indexed to, uint256 value)",
      "eventSignatureHash": "0xd3d3dd4b1fd3e53f94deb24e763485b4c925345c5abfa9ad529c67aa55a3b784",
      "isEnabled": true
    }
  }
}

Authorizations

​
Authorization
string
header
required

Circle's API Keys are formatted in the following structure "PREFIX:ID:SECRET". All three parts are requred to make a successful request.

Headers

​
X-Request-Id
string<uuid>

Developer-provided identifier for this request, used for tracing requests in Wallets API logs and the Developer Console, and when communicating with Circle Support. Must be a UUID to appear in logs. Non-UUID values are accepted by the API but are ignored by logging and tracing systems.

A unique identifier, which can be helpful for identifying a request when communicating with Circle support.

Example:

"2adba88e-9d63-44bc-b975-9b6ae3440dde"

Body

application/json

Create Event Monitor Request

​
blockchain
enum<string>
required

The blockchain network that the resource is to be created on or is currently on. Required along with sourceAddress if you don't provide walletId. The blockchain and walletId fields are mutually exclusive.

Available options:
ETH,
ETH-SEPOLIA,
MATIC,
MATIC-AMOY,
ARB,
ARB-SEPOLIA,
UNI,
UNI-SEPOLIA,
BASE,
BASE-SEPOLIA,
OP,
OP-SEPOLIA,
AVAX,
AVAX-FUJI,
ARC-TESTNET,
MONAD,
MONAD-TESTNET
Example:

"MATIC-AMOY"

​
contractAddress
string
required

The on-chain address of this contract.

Example:

"0x1e124d7384cd34448ea5907bd0052a79355ab5eb"

​
eventSignature
string
required

The specific event to which you want to subscribeven. Please ensure no spaces are included.

​
idempotencyKey
string<uuid>
required

Universally unique identifier (UUID v4) idempotency key. This key is utilized to ensure exactly-once execution of mutating requests. To create a UUIDv4 go to uuidgenerator.net. If the same key is reused, it will be treated as the same request and the original response will be returned.

Example:

"a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11"

Response

Event monitor already exists.

​
data
object
required