EVM Support

Flow supports running EVM transactions natively through its Cadence smart contract layer. FlowIndex automatically detects and indexes these EVM transactions, making them searchable by both their Flow transaction ID and their EVM hash.

How EVM Transactions Work on Flow

On Flow, EVM transactions are executed through Cadence transactions that import the EVM contract. When a Cadence transaction calls into the EVM environment, it emits an EVM.TransactionExecuted event containing the full EVM transaction details.

This means every EVM transaction on Flow has two identities:

A Flow transaction ID (the Cadence transaction that wrapped the EVM call)
An EVM transaction hash (the standard Ethereum-style hash)

Detection

FlowIndex detects EVM transactions during ingestion by checking for import EVM in the transaction script content. When detected:

The transaction's is_evm flag is set to true in raw.transactions
The evm_worker processes the block to extract detailed EVM data

EVM Worker Pipeline

The evm_worker runs as a Phase 1 processor in the deriver pipeline, processing blocks in parallel with other workers.

For each block, it:

Scans events for EVM.TransactionExecuted event types
Decodes the event payload to extract:
- EVM transaction hash
- From address (EVM sender)
- To address (EVM recipient)
- Value (amount transferred)
- Gas used
- EVM transaction status (success/failure)
Maps the EVM hash back to the parent Cadence transaction ID
Stores the mapping in app.evm_tx_hashes

A single Cadence transaction can contain multiple EVM transactions, so the mapping is one-to-many (one Flow tx ID to many EVM hashes).

Database Schema

`app.evm_tx_hashes`

Maps Cadence transaction IDs to EVM transaction hashes.

Column	Type	Description
`block_height`	bigint	Block height
`tx_id`	text	Flow (Cadence) transaction ID
`evm_hash`	text	EVM transaction hash (lowercase, no `0x` prefix)
`evm_from`	text	EVM sender address
`evm_to`	text	EVM recipient address
`evm_value`	numeric	Transfer value
`evm_gas_used`	bigint	Gas consumed
`evm_status`	smallint	Execution status

Storage Conventions

EVM hashes are stored lowercase without the 0x prefix
EVM addresses follow the same convention (lowercase, no 0x)
The raw.tx_lookup table stores EVM hashes in the evm_hash column for fast lookups

API Endpoints

List EVM Transactions

GET /flow/evm/transaction

Returns a paginated list of EVM transactions with their Flow and EVM identifiers.

Get EVM Transaction by Hash

GET /flow/evm/transaction/{hash}

Look up an EVM transaction by its EVM hash. Returns the EVM details along with the parent Cadence transaction.

The hash parameter accepts EVM hashes both with and without the 0x prefix.

Get Transaction by ID

GET /flow/transaction/{id}

This endpoint also resolves EVM hashes. If you pass an EVM hash as the {id}, it will find the corresponding Cadence transaction.

EVM Tokens

GET /flow/evm/token
GET /flow/evm/token/{address}
GET /flow/evm/address/{address}/token

Query EVM token contracts and address token holdings.

WebSocket

EVM transactions are included in the real-time WebSocket feed. The new_transaction message includes an is_evm field and an EVM tag:

{
  "type": "new_transaction",
  "payload": {
    "id": "abc123...",
    "block_height": 142610500,
    "is_evm": true,
    "tags": ["EVM"],
    "status": "SEALED",
    "execution_status": "SUCCESS"
  }
}

COA (Cadence-Owned Account) Mapping

Flow-EVM uses Cadence-Owned Accounts (COAs) to bridge between the Cadence and EVM environments. FlowIndex tracks COA creation events and provides a lookup endpoint:

GET /flow/coa/{address}

Returns the mapping between a Flow address and its associated EVM COA address.

EVM Support

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