> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstream.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Blockchain Core

> Raw blocks, transactions, gas metrics and chain-level state — when you need the facts beneath the normalized products.

The **Blockchain Core** data product is the raw substrate beneath everything else ChainStream publishes. Use it when you need facts that aren't expressed in the higher-level products (Tokens, Trades, Wallets), or when you're verifying / auditing something end-to-end.

<Note>
  Most integrations should start with Tokens / Trades / Wallets rather than here —
  the higher-level products are cheaper to query and already de-noised.
</Note>

## What's inside

| Dataset       | Key fields                                                                       |
| :------------ | :------------------------------------------------------------------------------- |
| Blocks        | `number`, `hash`, `parentHash`, `timestamp`, `gasUsed`, `baseFeePerGas`, `miner` |
| Transactions  | `hash`, `from`, `to`, `value`, `input`, `status`, `gasUsed`, `effectiveGasPrice` |
| Logs / Events | `txHash`, `logIndex`, `address`, `topics[]`, `data`, `removed`                   |
| Gas metrics   | `blockGasUsage`, `chainGasOracle` (EIP-1559 base / priority fees)                |
| Chain state   | `latestBlock`, `finality`, `reorgsLast1h`                                        |

## Coverage & freshness

* Raw data from every supported chain, back-filled to genesis where possible.
* Latency: blocks and logs delivered within 1–2 s of finalization.

## Access

<CardGroup cols={2}>
  <Card title="REST" icon="database" href="/en/api-reference/endpoint/data/blockchain/v2/blockchain-get">
    `/v2/blockchain`, `/v2/blockchain/{chain}/latest_block`.
  </Card>

  <Card title="Kafka" icon="tower-broadcast" href="/en/api-reference/kafka-topics/evm">
    `{chain}.dex.trades`, `{chain}.v1.transfers.proto`, `{chain}.balances` Protobuf topics per chain.
  </Card>

  <Card title="GraphQL" icon="diagram-project" href="/en/graphql/getting-started/overview">
    Query blocks joined with transactions and decoded events.
  </Card>

  <Card title="SDK" icon="box" href="/en/sdks/overview">
    Typed wrappers for blocks/transactions/logs.
  </Card>
</CardGroup>

## Common use cases

* Independent verification of a higher-level data point
* Custom indexing pipelines that need raw logs
* Gas-price oracles and fee-estimation services
* Chain-health dashboards (reorgs, uncle rate, base-fee drift)

## Billing

Raw-data endpoints charge per item returned. Kafka topics priced per delivered message, discounted in streaming tiers.

## Next

<CardGroup cols={2}>
  <Card title="Kafka topic catalog" icon="tower-broadcast" href="/en/api-reference/kafka-topics/evm">
    Per-chain list of raw topics and schemas.
  </Card>

  <Card title="Data freshness & SLA" icon="gauge-high" href="/en/docs/data-products/data-freshness">
    Latency expectations per chain and per surface.
  </Card>
</CardGroup>