UTXO

A UTXO is an unspent transaction output: a discrete amount of coin locked by a script that a later transaction consumes as an input to spend it.

Bitcoin does not track account balances; it tracks unspent transaction outputs. Each output is a fixed amount locked to a spending condition, and a transaction spends whole UTXOs as inputs, creating new outputs including change. A wallet's balance is the sum of the UTXOs it can unlock. This model enables parallel validation and clear provenance but requires coin selection when building spends. Our Bitcoin archive RPC exposes the full UTXO set and historical output state, so you can select inputs, compute balances, and trace value flow across the chain.