Please note that a blockchain (Bitcoin, Ethereum, etc.) transaction hash is merely an identifier that a transaction was accepted by a node but not a guarantee that it is going to be included in the network. Multiple factors like low gas amount/network fee or insufficient gas price may cause a transaction to never get broadcasted to the network and to be discarded eventually. It is only safe to assume the transaction as valid when it changes to the "confirmed" state via  `GET /[blockchain]/`tx/:hash`