QuickSync is a fast wallet synchronization feature built on the Waterfalls protocol, an open-source descriptor-based sync protocol developed by Blockstream's Riccardo Casatta. QuickSync allows wallets to retrieve complete transaction history or unspent outputs (UTXOs) in a single API call instead of checking addresses one by one. By sharing a descriptor once, the wallet receives all relevant transaction data from the server in a single structured response, reducing sync time from hours to minutes. QuickSync offers flexible sync modes: full transaction history for complete wallet restoration, UTXO-only sync for faster transaction creation (since the wallet only needs to know what it has available to spend), and last index retrieval for finding unused addresses.

Available through the Blockstream Explorer API REST interface across all subscription tiers.