EVM Transactions

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

Public RPC URLs enforce rate limits per IP address and can fail under concurrent load. Use a private endpoint (Alchemy, Infura, QuickNode, or self-hosted). See Connecting to any chain.

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 '@zafeguard/caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.ZAFEGUARD_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..."

BUILD_EVM_TRANSFER_CALLDATA

BUILD_EVM_TRANSFER_CALLDATA Workflow Component

Convenience wrapper around BUILD_EVM_CALLDATA for the common case of sending native ETH or an ERC-20 transfer. Picks the right encoding automatically:

tokenAddress is null → native ETH transfer. Returns calldata: "0x", to: recipient, value: amount.
tokenAddress set → ERC-20 transfer(recipient, amount). Returns the encoded calldata, to: tokenAddress, value: "0x0".

The output plugs directly into BUILD_EVM_TRANSACTION.

Inputs

Field	Type	Description
`recipient`	`string` (address)	Recipient address
`amount`	`string` (bigint)	Amount in the token's smallest unit (wei for ETH)
`tokenAddress`	`string \| null`	ERC-20 contract — omit/null for native ETH

Outputs

Field	Type	Description
`calldata`	`string`	ABI-encoded transfer calldata, or `0x` for native ETH
`to`	`string`	Token contract address (ERC-20) or recipient (ETH)
`value`	`string`	ETH value to send (`0x0` for ERC-20, `amount` for native)

BUILD_EVM_ERC20_APPROVE_CALLDATA

BUILD_EVM_ERC20_APPROVE_CALLDATA Workflow Component

ABI-encode an ERC-20 approve(spender, amount) call. The standard upstream step before any operation that pulls tokens via transferFrom — bridges, DEX swaps, lending deposits, vault entries.

Pass amount = 2^256 - 1 (max uint256) for an infinite approval.

Inputs

Field	Type	Description
`tokenAddress`	`string` (address)	ERC-20 contract to approve against
`spender`	`string` (address)	Address allowed to pull tokens (e.g. a bridge router, a Uniswap router, a vault)
`amount`	`string` (bigint)	Allowance in the token's smallest unit

Outputs

Field	Type	Description
`calldata`	`string`	ABI-encoded `approve(spender, amount)` calldata
`to`	`string`	The ERC-20 contract address (forwarded from input)
`value`	`string`	Always `"0x0"` — `approve` is a non-payable call

The output plugs directly into BUILD_EVM_TRANSACTION.

SDK example

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

const approve = await workspace.call(ComponentModule.BUILD_EVM_ERC20_APPROVE_CALLDATA, {
  tokenAddress: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', // USDC on Ethereum
  spender:      '0xc026395860Db2d07ee33e05fE50ed7bD583189C7', // bridge router
  amount:       '1000000', // 1 USDC (6 decimals)
}).promise();

// Feed into BUILD_EVM_TRANSACTION → SIGN → BROADCAST → WAIT

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`
`estimatedFee`	`string` (bigint)	Estimated maximum gas fee in wei. For LEGACY: `gasLimit × gasPrice`. For EIP1559: `gasLimit × maxFeePerGas`. `gasLimit` includes a 20% safety buffer

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

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...`)

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)

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

Full transaction workflow

import { WorkspaceClient, ComponentModule } from '@zafeguard/caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.ZAFEGUARD_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

EVM Transactions

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