The Pooled UTXO Model is a Bitcoin privacy and fee-optimization technique that groups multiple users\' unspent transaction outputs (UTXOs) — such as in CoinJoin — into collective on-chain transactions. By combining UTXOs from several participants, it breaks the transaction graph that blockchain analysts use to track funds, dramatically improving privacy.
Bitcoin\'s UTXO model manages ownership by tracking discrete, indivisible units of Bitcoin rather than account balances. Each UTXO is cryptographically locked to an owner\'s public key and can only be spent by providing a valid digital signature. The sum of all UTXOs in your wallet equals your Bitcoin balance.
How the Pooled UTXO Model Works
BITCOIN'S TRANSACTION ARCHITECTURE
Every Bitcoin transaction consumes existing UTXOs as inputs and creates new UTXOs as outputs. When you send Bitcoin, your wallet selects UTXOs to cover the amount, sends the recipient a new UTXO, and returns any change as another new UTXO. The Pooled UTXO Model extends this by allowing multiple users to pool their UTXOs together in a single transaction, reducing individual fees and obscuring the transaction graph for privacy.
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