Transaction Index (txindex)

txindex is a Bitcoin Core configuration option (-txindex=1 in bitcoin.conf) that builds and maintains a database mapping every transaction ID to its location in the block files. With it enabled, getrawtransaction <txid> returns any transaction in the chain's history immediately. Without it, that RPC only works for transactions still in the mempool or in the wallet's known set.

What txindex costs:

• Disk. Roughly 50-70 GB of additional storage in 2026, growing with the chain. Compared to ~600 GB for the archival block data, it's not the biggest add, but it's not negligible either.
• Initial sync time. The index gets built during the initial validation pass; expect IBD to be somewhat slower. After the index is built, ongoing operation is unaffected.
• Incompatibility with pruning. txindex requires archival mode. Pruned nodes can't maintain a full transaction index because they don't keep all the blocks.

Who needs it:

• Block explorers. Mempool.space, Blockstream Explorer, and similar tools need to look up arbitrary transactions on demand. They run txindex=1 against archival nodes (or use their own custom databases derived from the chain).
• Chain analysis tools that work with arbitrary historical transactions.
• Some specialized wallets that need to walk historical UTXO graphs (rare; modern descriptor wallets typically only track their own outputs).
• Lightning node operators in some configurations, though most LN backends don't strictly require txindex.

Who doesn't need it: every standard wallet user. Wallets only track UTXOs that belong to them; they have all the relevant transactions in their own wallet database. Trying to look up an arbitrary unrelated transaction is something users essentially never do outside of explorer-style workflows.

Default is off. Turn it on only if you actually need it. If you're running a node for personal wallet use plus optional peer service, leaving txindex off saves disk and lets you run with pruning if you want.