<p>You need a way of querying the unspent pool in order to do this. A workaround is to lookup the transaction that is being referenced via some public api, blockchain etc, and check the referenced output as they usually mark them as spent/unspent. You can do this programatically by querying for all unspents for the addresses referenced by the output in question and filtering it for the one you want.</p>

CC BY-SA 3.0
2014-11-26T23:46:33.307Z
2014-11-26T23:46:33.307Z
Matt
<p>I want to know if a certain output is spent. I am not using bitcoind, I do not have a gettxout RPC call available. How can I learn if a vout is referenced as an input somewhere in the blockchain or accepted mempool?</p>

<p>I don't mean just for my wallet, I want to know if an output has been spent on the network somewhere.</p>

<transactions><utxo>
How can I find out if a transaction used a specific vout as its input?
Matthew Darnell
# How can I find out if a transaction used a specific vout as its input?

(Asked by: username_0 on 2014-11-26)

I want to know if a certain output is spent. I am not using bitcoind, I do not have a gettxout RPC call available. How can I learn if a vout is referenced as an input somewhere in the blockchain or accepted mempool?

I don't mean just for my wallet, I want to know if an output has been spent on the network somewhere.

**Tags:** transactions, utxo


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## 1 answers

### Answer by username_1 on 2014-11-26. Score: 1

You need a way of querying the unspent pool in order to do this. A workaround is to lookup the transaction that is being referenced via some public api, blockchain etc, and check the referenced output as they usually mark them as spent/unspent. You can do this programatically by querying for all unspents for the addresses referenced by the output in question and filtering it for the one you want.


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