Bitcoin Core ZMQ messaging system has hashtx along with 4 other topics. But nowhere it is documented whether the transactions that comes from hashtx are confirmed transactions which are added in a block or unconfirmed transactions that is yet to mined.

1 Answer 1


Both. A notification will be sent when a transaction is added to the mempool. For newly added blocks, a notification will be sent for every transaction in that block, so when a transaction is confirmed, there will be a notification for it.

  • Thanks @Andrew, So two notification will be coming, one when sent to mempool and another when it got added in the block right ? Oct 21, 2020 at 6:58
  • Yes, that is correct.
    – Ava Chow
    Oct 21, 2020 at 15:51

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