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This section provides details about ChainStream’s EVM Streams via Kafka. The top-level Kafka section explains how we use Kafka Streams to deliver data. EVM blockchains produce blocks at varying intervals depending on the network. Ethereum mainnet targets ~12 seconds per block, while other EVM chains may have different block times.

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Structure of On-Chain Data

The EVM Protobuf Streams provide two main message types for different use cases:
  • BlockMessage: Full blocks with detailed transaction and header data
  • TransfersMessage: Focused on token transfers with currency metadata

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BlockHeader

Represents metadata about a block.
  • Hash: Unique identifier of the block
  • ParentHash: Hash of the parent block
  • UncleHash: Hash of uncle/ommer blocks (Ethereum PoW)
  • Root: State root of the block
  • TxHash: Root hash of all transactions
  • ReceiptHash: Root hash of all receipts
  • MixDigest: Proof-of-work mix digest (legacy)
  • Coinbase: Miner/validator address
  • Bloom: Bloom filter for logs
  • Extra: Extra data field
  • Nonce: Block nonce (legacy PoW)
  • Difficulty: Mining difficulty (legacy PoW)
  • Number: Block height
  • GasLimit: Maximum gas allowed in this block
  • GasUsed: Actual gas consumed
  • Time: Block timestamp (seconds since epoch)
  • BaseFee: Base fee per gas (EIP-1559)
  • SequenceNumber: Optimism-specific sequence number
  • BatcherAddr: Optimism-specific batcher address
  • L1FeeOverhead: Optimism-specific L1 fee overhead
  • L1FeeScalar: Optimism-specific L1 fee scalar

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TransactionHeader

Represents metadata about a transaction.
  • Index: Transaction index in the block
  • Hash: Transaction hash
  • GasUsed: Gas actually consumed
  • GasLimit: Gas limit specified
  • Value: Amount of native currency transferred
  • Data: Input call data
  • Nonce: Sender account nonce
  • ChainId: Chain ID of the transaction
  • Cost: Total cost (gas × price + value)
  • GasFeeCap: Max fee per gas (EIP-1559)
  • GasPrice: Legacy gas price
  • GasTipCap: Max priority fee per gas
  • Protected: Whether replay protection is enabled
  • Type: Transaction type (e.g. 2 for EIP-1559, 3 for EIP-4844)
  • To: Recipient address
  • From: Sender address
  • ToCode: Code metadata of the recipient contract
  • AccessList: Access list (EIP-2930)
  • GasL1: Arbitrum-specific L1 gas usage
  • IsSystemTx: Optimism-specific system transaction flag
  • EffectiveNonce: Optimism-specific effective nonce
  • SourceHash: Optimism-specific source hash
  • Time: Broadcast timestamp (optional)
  • Blob: EIP-4844 blob data (hashes, proofs, commitments, gas, fee cap)

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Transfer

Represents a token or native currency transfer.
  • CallIndex: Index of the call within the transaction
  • LogIndex: Index of the log within the block
  • Sender: Address sending tokens
  • Receiver: Address receiving tokens
  • Amount: Amount of tokens transferred (string for precision)
  • Id: Token ID (for NFTs)
  • URI: Token URI (for NFTs with metadata)
  • Currency: TokenInfo metadata about the token
  • Success: Whether the transfer succeeded
  • Data: Raw event data
  • Index: Transfer index within the message
  • TransactionHeader: Transaction context for this transfer

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TokenInfo

Metadata about a token.
  • SmartContract: Token contract address
  • Delegated: Whether the token is delegated
  • DelegatedTo: Address to which it is delegated
  • ProtocolName: Protocol/project name
  • Name: Token name
  • Symbol: Token symbol
  • Decimals: Number of decimal places
  • HasURI: Whether the token has a URI field
  • Fungible: Whether the token is fungible (ERC-20) or non-fungible (ERC-721/1155)
  • AssetId: Unique asset identifier
  • Standard: Token standard (NATIVE, ERC20, ERC721, ERC1155)

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TransfersMessage

Top-level message for transfer streams.
  • Chain: Blockchain metadata (ChainId, Config)
  • Header: Block header of the current block
  • Transfers: List of Transfer records
  • L1Header: Optional L1 block header (for L2 chains)

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Chain

  • ChainId: Unique identifier of the blockchain
  • Config: Chain configuration string

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Blob (EIP-4844)

  • Hashes: Blob hashes
  • Proofs: Blob proofs
  • Commitments: Blob commitments
  • BlobGas: Gas used for blobs
  • BlobGasFeeCap: Fee cap for blob gas

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Layer 2 Support

EVM Protobuf Streams provide dedicated fields for Layer 2 chains:
  • L1Header: Corresponding L1 block information
  • Optimism-specific: SequenceNumber, BatcherAddr, L1FeeOverhead, L1FeeScalar, IsSystemTx, EffectiveNonce, SourceHash
  • Arbitrum-specific: GasL1
  • EIP-4844: Blob structure for blob-carrying transactions

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Using This Stream

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Topic Names

The EVM streams are available under different topics:
  • eth.v1.transfers.proto → TransfersMessage
  • bsc.v1.transfers.proto → TransfersMessage
  • polygon.v1.transfers.proto → TransfersMessage
  • eth.broadcasted.v1.transfers.proto → TransfersMessage
  • bsc.broadcasted.v1.transfers.proto→TransfersMessage
  • eth.broadcasted.v1.transfers.processed.proto → TransfersMessage
  • bsc.broadcasted.v1.transfers.processed.proto→TransfersMessage