Definition
UTXO labeling is the practice of attaching human-readable notes to the records in a wallet: individual transactions, addresses, inputs, outputs, and extended public keys. Because Bitcoin uses an unspent-transaction-output model with no built-in memo field, labels are the only way to remember where a given coin came from, why it was received, and whether it is safe to spend alongside another coin. Good labels turn an anonymous list of UTXOs into an auditable ledger you actually understand.
Why labels are a sovereignty tool
Labels are the data layer that makes effective coin control possible. Knowing that one output came from a KYC exchange while another came from a peer-to-peer trade lets you avoid merging them and leaking that link on-chain. Labels also support honest bookkeeping for tax and accounting without surrendering custody to a third-party tracking service.
The BIP329 standard
Historically each wallet stored labels in a proprietary format, locking your annotations to one app. BIP329 defines a portable export using JSON Lines, where each line records a type, a reference, and an optional label and spendable flag. This lets you migrate years of carefully built context between wallets. Because the data is privacy-sensitive, the standard recommends encrypting it whenever it crosses an untrusted network.
Maintain your labels alongside a robust wallet backup, since a seed phrase restores your coins but never your context.
In Simple Terms
UTXO labeling is the practice of attaching human-readable notes to the records in a wallet: individual transactions, addresses, inputs, outputs, and extended public keys. Because…