An indexer parses blockchain data and serves structured queries for apps, enabling fast lookups beyond what a raw full node provides.
Indexers read blocks, transactions, and logs into databases optimized for queries like balances, histories, and events. They power explorers, wallets, and analytics.
"A wallet can query an indexer for an address history instead of scanning the entire chain each time."
"Explorers use indexers to aggregate mempool and block data for charts and statistics."
Indexers add convenience but introduce trust and liveness assumptions. Self-hosting reduces reliance on third parties; open APIs improve accessibility but can censor or rate-limit.
"Running a local indexer gives privacy and reliability, at the cost of storage and maintenance."
"Decentralized indexing networks attempt to distribute indexing work among many operators."
All terms and definitions may update as the Cryptionary improves.