To create an unsigned transaction via this endpoint, you need an unspent transaction output (UTXO), that can be specified by a transaction hash and an index. For example, it’s fine to pick any transaction hash and index of a UTXO (just remember that it has to be unspent, otherwise, the request will fail as you can’t spend a transaction output more than once).

By using the REST API’s Get A List of Transactions endpoint, you can get outputs for the latest transactions in the network. You can get the UTXO in the response. UTXOs are represented in the REST API by the event type utxo_output. You can now, pass the transaction hash of the output, and its index to the respective fields: from and index.

Supported Protocols and Networks