BlockonomicsAPI Reference
POST/monitor_txAuth required

Monitor USDT Transaction

Begin tracking a USDT transaction.

Once monitoring is started, our system will send HTTP callbacks to your configured endpoint whenever the transaction status changes. The callback format and delivery rules follow the same pattern as described in the [Callback Notification documentation](https://developers.blockonomics.co/reference/callback-notification#/).

About testnet - Accepts only numeric values (0 or 1). - 0 = mainnet, 1 = sepolia testnet. - Defaults to 0 (mainnet) if omitted.

About status in callbacks For USDT transactions, the status integer in the callback payload reflects the exact blockchain confirmation count at the time the callback is sent. Callbacks are only sent when the status changes to one of the following values: - -1 = Reverted (failed or dropped from mempool) - 0 = Exactly 0 confirmations (unconfirmed) - 1 = Exactly 1 confirmation - 2 = Exactly 2 confirmations — this is the final status reported by our system. We do not send callbacks for 3 or more confirmations. If you require tracking beyond 2 confirmations, you must query the blockchain directly.

Other callback fields include: - addr: Receiving address - value: Payment amount in the smallest unit (for USDT, in token base units) - txid: Transaction hash

Requires Bearer token authentication. Include Authorization: Bearer YOUR_API_KEY in the request header.

Request Body

txhashstringrequired

The transaction hash to monitor.

cryptostringrequired

The cryptocurrency used (USDT).

match_callbackstringrequired

String to match part of your [Store](https://developers.blockonomics.co/reference/get_v2-stores#/) callback URL, used when you have multiple stores to ensure the correct one is matched.

testnetintegerrequired

Indicates if the transaction is on the testnet. `0` = mainnet, `1` = sepolia testnet. Defaults to `0` if omitted.

Responses

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txhashbody · stringrequired

The transaction hash to monitor.

cryptobody · stringrequired

The cryptocurrency used (USDT).

match_callbackbody · stringrequired

String to match part of your [Store](https://developers.blockonomics.co/reference/get_v2-stores#/) callback URL, used when you have multiple stores to ensure the correct one is matched.

testnetbody · integerrequired

Indicates if the transaction is on the testnet. `0` = mainnet, `1` = sepolia testnet. Defaults to `0` if omitted.

Response will appear here