Coin Control
A wallet feature that lets a user manually choose which specific UTXOs to spend in a transaction, rather than letting the wallet select automatically.
Coin control is a wallet feature, common in Bitcoin and other UTXO-model wallets, that gives the user direct, manual control over which specific unspent transaction outputs (UTXOs, see Kaavon's "UTXO" glossary definition) are consumed as inputs to a new transaction, rather than leaving that selection entirely to the wallet's automatic coin-selection algorithm. Without coin control, a wallet typically combines whichever UTXOs it judges most efficient, which can unintentionally merge funds from unrelated sources into a single transaction.
Coin control matters for both privacy and cost management: manually avoiding combining UTXOs from different, unrelated sources helps prevent accidentally linking them together through entity clustering (see Kaavon's "Entity Clustering" glossary definition) and avoiding address reuse (see Kaavon's "Address Reuse" glossary definition), while manually selecting larger UTXOs over many small ones can reduce transaction fees. The tradeoff is that coin control requires more manual effort and UTXO-management awareness than simply letting the wallet choose automatically.
Examples
- A privacy-conscious user might use coin control to ensure a payment draws only from UTXOs that haven't been linked to their other activity, rather than letting the wallet combine them automatically.
- Using coin control to select a few larger UTXOs instead of many small ones can meaningfully reduce the fee paid on a transaction, since each additional input adds to the transaction's size.