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Blockchain data infrastructure, explained
Guides to blockchain indexers, onchain data APIs, and the infrastructure underneath them. Written by the SQD team.
What is a wallet history API?
Address-keyed access to transaction history, balances, and token holdings. What wallets, accounting tools, and tax software need.
Compliance data for crypto: what regulators and investigators look at
Transaction traces, state diffs, attribution data, and the chain-of-custody requirements regulated entities work with. What goes into a Travel Rule submission.
AI agents and onchain data: what an agent needs to act on blockchain state
What an agent actually needs from onchain data, the Model Context Protocol (MCP) pattern, and how on-demand and pre-indexed pipelines differ in agent workflows.
The blockchain data stack in 2026
A reference architecture for onchain data: nodes, indexers, APIs, warehouses, and analytics. The layers, the trade-offs, and named providers at each tier.
Blockchain data API: a complete guide
RPC, indexed data, decentralized networks, and market data APIs. What each does and when to use them.
What is an EVM indexer?
The data model EVM chains share, what an EVM indexer must handle, and how indexing patterns translate across Ethereum, Base, Arbitrum, Polygon, and BNB.
What is a blockchain indexer?
How indexers work, the types of indexer that exist today, and how teams choose one.
Multi-chain indexing explained
How to index data from many blockchains into one schema, the validation problem, and common architectural patterns.
What is a Solana indexer?
The Solana data model, the discriminator system, fork handling, and the SVM family. Concrete details from SQD's production Solana data lake.
What is a subgraph?
Subgraphs explained: the data model, mappings, schema.graphql, and what migrating one to another stack involves.
RPC vs indexed data: which do you actually need?
When an RPC endpoint is enough, when you need an indexer, and the costs of each.