EVM Transactions

Components for the full EVM transaction lifecycle: calldata encoding → transaction building → signing → broadcasting → confirmation.

Avoid public RPC endpoints

White Rabbit runs on shared infrastructure with a shared outbound IP pool. Public RPC URLs enforce rate limits per IP — under load this can cause errors across all workspaces sharing that IP. Use a private endpoint (Alchemy, Infura, QuickNode, or self-hosted). See Connecting to any chain.

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BUILD_EVM_CALLDATA

BUILD_EVM_CALLDATA Workflow Component

ABI-encode a contract function call into hex calldata.

Config

Field	Type	Required	Description
functionName	string	Yes	Name of the contract function to encode (e.g. "transfer")

Inputs

Field	Type	Description
abi	AbiItem[]	Contract ABI (array of function/event definitions)
args	string[]	Function arguments in order, as strings

Outputs

Field	Type	Description
calldata	string	ABI-encoded hex calldata (0x...)

SDK example

import { WorkspaceClient, ComponentModule } from 'caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.WR_API_KEY! });

const result = await workspace.call(ComponentModule.BUILD_EVM_CALLDATA, {
  abi: [
    {
      type: 'function',
      name: 'transfer',
      inputs: [
        { name: 'to', type: 'address' },
        { name: 'amount', type: 'uint256' },
      ],
      outputs: [{ name: '', type: 'bool' }],
      stateMutability: 'nonpayable',
    },
  ],
  args: ['0xRecipientAddress', '1000000'],
}).promise();
console.log(result.calldata); // "0xa9059cbb..."

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BUILD_EVM_TRANSACTION

BUILD_EVM_TRANSACTION Workflow Component

Construct a complete unsigned EVM transaction object. Estimates gas automatically.

Config

Field	Type	Default	Description
type	'LEGACY' | 'EIP1559'	'EIP1559'	Transaction type. Use LEGACY for chains that don't support EIP-1559
deductFee	boolean	false	Subtract estimated gas fee from value. Useful when sending the full native balance

Inputs

Field	Type	Required	Description
jsonRpcUrl	string	Yes	JSON-RPC endpoint
from	string	Yes	Sender address
to	string	Yes	Recipient or contract address
value	string	No	Native token amount to send in wei (bigint string, default "0")
calldata	string	No	ABI-encoded calldata (0x...). Omit for plain transfers
gasLimit	string	No	Manual gas limit override (bigint string). Auto-estimated if omitted

Outputs

Field	Type	Description
unsignedTransaction	string	RLP-encoded unsigned transaction hex
serializedHash	string	Transaction hash pre-image — pass directly to SIGN_WITH_KEY_SHARE

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SIGN_EVM_TRANSACTION

SIGN_EVM_TRANSACTION Workflow Component

Combine an unsigned transaction with an MPC signature to produce a signed transaction ready for broadcast.

Config

None.

Inputs

Field	Type	Description
unsignedTransaction	string	Output of BUILD_EVM_TRANSACTION
signature	string	ECDSA signature from SIGN_WITH_KEY_SHARE

Outputs

Field	Type	Description
signedTransaction	string	RLP-encoded signed transaction hex

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BROADCAST_EVM_TRANSACTION

BROADCAST_EVM_TRANSACTION Workflow Component

Submit a signed transaction to the network and return the transaction hash.

Config

None.

Inputs

Field	Type	Description
jsonRpcUrl	string	JSON-RPC endpoint
signedTransaction	string	Output of SIGN_EVM_TRANSACTION

Outputs

Field	Type	Description
transactionHash	string	Transaction hash (0x...)

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WAIT_FOR_EVM_TRANSACTION

WAIT_FOR_EVM_TRANSACTION Workflow Component

Block execution until a transaction is confirmed on-chain. Useful for sequencing dependent transactions.

Config

Field	Type	Default	Description
confirmations	number	1	Number of block confirmations to wait for before resolving (1–25)

Inputs

Field	Type	Description
jsonRpcUrl	string	JSON-RPC endpoint
transactionHash	string	Transaction hash to monitor (0x..., 32 bytes)

Outputs

Field	Type	Description
blockNo	number	Block number in which the transaction was included
gasUsed	number	Actual gas consumed by the transaction
gasPrice	string	Effective gas price in wei (bigint string)
gasFee	string	Total gas fee paid in wei — gasUsed × gasPrice (bigint string)

tip

WAIT_FOR_EVM_TRANSACTION is billed PER_EXECUTION_TIME — confirmations on congested chains can take minutes. Consider your credit budget.

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Full transaction workflow

import { WorkspaceClient, ComponentModule } from 'caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.WR_API_KEY! });

const path = await workspace.call(ComponentModule.GET_EVM_DERIVATION_PATH, { addressIndex: 0 }).promise();
const pubKey = await workspace.call(ComponentModule.COMPUTE_PUBLIC_KEY, {
  keyId: 'my-key-id',
  derivationPath: path.derivationPath,
}).promise();
const address = await workspace.call(ComponentModule.COMPUTE_EVM_ADDRESS, {
  publicKey: pubKey.publicKey,
}).promise();
const calldata = await workspace.call(ComponentModule.BUILD_EVM_CALLDATA, {
  abi: ERC20_ABI,
  args: [recipientAddress, '1000000'],
}).promise();
const unsignedTx = await workspace.call(ComponentModule.BUILD_EVM_TRANSACTION, {
  jsonRpcUrl: RPC_URL,
  from: address.address,
  to: TOKEN_CONTRACT,
  value: '0',
  calldata: calldata.calldata,
}).promise();
// ... sign and broadcast