Guide: Integrating the Safe Core SDK

1. Install the dependencies

To integrate the Safe Core SDK into your Dapp or script you will need to install these dependencies:

@safe-global/safe-core-sdk-types
@safe-global/safe-core-sdk
@safe-global/safe-service-client

And one of these two:

@safe-global/safe-web3-lib
@safe-global/safe-ethers-lib

First of all, we need to create an EthAdapter, which contains all the required utilities for the SDKs to interact with the blockchain. It acts as a wrapper for web3.js or ethers.js Ethereum libraries.

Depending on the library used by the Dapp, there are two options:

Create an EthersAdapter instance
Create a Web3Adapter instance

Once the instance of EthersAdapter or Web3Adapter is created, it can be used in the SDK initialization.

Initialize the Safe Service Client

As stated in the introduction, the Safe Service Client consumes the Safe Transaction Service API. To start using this library, create a new instance of the SafeServiceClient class, imported from @safe-global/safe-service-client and pass the URL to the constructor of the Safe Transaction Service you want to use depending on the network.

import SafeServiceClient from '@safe-global/safe-service-client'

const txServiceUrl = 'https://safe-transaction-mainnet.safe.global'
const safeService = new SafeServiceClient({ txServiceUrl, ethAdapter })

Initialize the Safe Core SDK

import Safe, { SafeFactory } from '@safe-global/safe-core-sdk'

const safeFactory = await SafeFactory.create({ ethAdapter })

const safeSdk = await Safe.create({ ethAdapter, safeAddress })

There are two versions of the Safe contracts: GnosisSafe.sol that does not trigger events in order to save gas and GnosisSafeL2.sol that does, which is more appropriate for L2 networks.

By default GnosisSafe.sol will be only used on Ethereum Mainnet. For the rest of the networks where the Safe contracts are already deployed, the GnosisSafeL2.sol contract will be used unless you add the property isL1SafeMasterCopy to force the use of the GnosisSafe.sol contract.

const safeFactory = await SafeFactory.create({ ethAdapter, isL1SafeMasterCopy: true })

const safeSdk = await Safe.create({ ethAdapter, safeAddress, isL1SafeMasterCopy: true })

If the Safe contracts are not deployed to your current network, the property contractNetworks will be required to point to the addresses of the Safe contracts previously deployed by you.

import { ContractNetworksConfig } from '@safe-global/safe-core-sdk'

const chainId = await ethAdapter.getChainId()
const contractNetworks: ContractNetworksConfig = {
  [chainId]: {
    safeMasterCopyAddress: '<MASTER_COPY_ADDRESS>',
    safeProxyFactoryAddress: '<PROXY_FACTORY_ADDRESS>',
    multiSendAddress: '<MULTI_SEND_ADDRESS>',
    multiSendCallOnlyAddress: '<MULTI_SEND_CALL_ONLY_ADDRESS>',
    fallbackHandlerAddress: '<FALLBACK_HANDLER_ADDRESS>',
    signMessageLibAddress: '<SIGN_MESSAGE_LIB_ADDRESS>',
    createCallAddress: '<CREATE_CALL_ADDRESS>',
    safeMasterCopyAbi: '<MASTER_COPY_ABI>', // Optional. Only needed with web3.js
    safeProxyFactoryAbi: '<PROXY_FACTORY_ABI>', // Optional. Only needed with web3.js
    multiSendAbi: '<MULTI_SEND_ABI>', // Optional. Only needed with web3.js
    multiSendCallOnlyAbi: '<MULTI_SEND_CALL_ONLY_ABI>', // Optional. Only needed with web3.js
    fallbackHandlerAbi: '<FALLBACK_HANDLER_ABI>', // Optional. Only needed with web3.js 
    signMessageLibAbi: '<SIGN_MESSAGE_LIB_ABI>', // Optional. Only needed with web3.js
    createCallAbi: '<CREATE_CALL_ABI>' // Optional. Only needed with web3.js
  }
}

const safeFactory = await SafeFactory.create({ ethAdapter, contractNetworks })

const safeSdk = await Safe.create({ ethAdapter, safeAddress, contractNetworks })

The SafeFactory constructor also accepts the property safeVersion to specify the Safe contract version that will deploy. This string can take the values 1.1.1, 1.2.0 or 1.3.0. If not specified, the most recent contract version will be used by default.

const safeVersion = 'X.Y.Z'
const safeFactory = await SafeFactory.create({ ethAdapter, safeVersion })

3. Deploy a new Safe

The Safe Core SDK library allows the deployment of new Safes using the safeFactory instance we just created.

Here, for example, we can create a new Safe account with 3 owners and 2 required signatures.

import { SafeAccountConfig } from '@safe-global/safe-core-sdk'

const safeAccountConfig: SafeAccountConfig = {
  owners: ['0x...', '0x...', '0x...']
  threshold: 2,
  // ... (optional params)
}
const safeSdk = await safeFactory.deploySafe({ safeAccountConfig })

Calling the method deploySafe will deploy the desired Safe and return a Safe Core SDK initialized instance ready to be used. Check the API Reference for more details on additional configuration parameters and callbacks.

4. Create a transaction

The Safe Core SDK supports the execution of single Safe transactions but also MultiSend transactions. We can create a transaction object by calling the method createTransaction in our Safe instance.

Create a single transaction

This method can take an object of type SafeTransactionDataPartial that represents the transaction we want to execute (once the signatures are collected). It accepts some optional properties as follows.

import { SafeTransactionDataPartial } from '@safe-global/safe-core-sdk-types'

const safeTransactionData: SafeTransactionDataPartial = {
  to,
  data,
  value,
  operation, // Optional
  safeTxGas, // Optional
  baseGas, // Optional
  gasPrice, // Optional
  gasToken, // Optional
  refundReceiver, // Optional
  nonce // Optional
}

const safeTransaction = await safeSdk.createTransaction({ safeTransactionData })

Create a MultiSend transaction

This method can take an array of MetaTransactionData objects that represent the multiple transactions we want to include in our MultiSend transaction. If we want to specify some of the optional properties in our MultiSend transaction, we can pass a second argument to the method createTransaction with the SafeTransactionOptionalProps object.

import { SafeTransactionOptionalProps } from '@safe-global/safe-core-sdk'
import { MetaTransactionData } from '@safe-global/safe-core-sdk-types'

const safeTransactionData: MetaTransactionData[] = [
  {
    to,
    data,
    value,
    operation
  },
  {
    to,
    data,
    value,
    operation
  },
  // ...
]

const options: SafeTransactionOptionalProps = {
  safeTxGas, // Optional
  baseGas, // Optional
  gasPrice, // Optional
  gasToken, // Optional
  refundReceiver, // Optional
  nonce // Optional
}

const safeTransaction = await safeSdk.createTransaction({ safeTransactionData, options })

We can specify the nonce of our Safe transaction as long as it is not lower than the current Safe nonce. If multiple transactions are created but not executed they will share the same nonce if no nonce is specified, validating the first executed transaction and invalidating all the rest. We can prevent this by calling the method getNextNonce from the Safe Service Client instance. This method takes all queued/pending transactions into account when calculating the next nonce, creating a unique one for all different transactions.

const nonce = await safeService.getNextNonce(safeAddress)

5. Propose the transaction to the service

Once we have the Safe transaction object we can share it with the other owners of the Safe so they can sign it. To send the transaction to the Safe Transaction Service we need to call the method proposeTransaction from the Safe Service Client instance and pass an object with the properties:

safeAddress: The Safe address.
safeTransactionData: The data object inside the Safe transaction object returned from the method createTransaction.
safeTxHash: The Safe transaction hash, calculated by calling the method getTransactionHash from the Safe Core SDK.
senderAddress: The Safe owner or delegate proposing the transaction.
senderSignature: The signature generated by signing the safeTxHash with the senderAddress.
origin: Optional string that allows to provide more information about the app proposing the transaction.

const safeTxHash = await safeSdk.getTransactionHash(safeTransaction)
const senderSignature = await safeSdk.signTransactionHash(safeTxHash)
await safeService.proposeTransaction({
  safeAddress,
  safeTransactionData: safeTransaction.data,
  safeTxHash,
  senderAddress,
  senderSignature: senderSignature.data,
  origin
})

6. Get the transaction from the service

The transaction is then available on the Safe Transaction Service and the owners can retrieve it by finding it in the pending transaction list, or by getting its Safe transaction hash.

Get a list of pending transactions:

const pendingTxs = await safeService.getPendingTransactions(safeAddress)

Get a specific transaction given its Safe transaction hash:

const tx = await safeService.getTransaction(safeTxHash)

The retrieved transaction will have this type:

type SafeMultisigTransactionResponse = {
  safe: string
  to: string
  value: string
  data?: string
  operation: number
  gasToken: string
  safeTxGas: number
  baseGas: number
  gasPrice: string
  refundReceiver?: string
  nonce: number
  executionDate: string
  submissionDate: string
  modified: string
  blockNumber?: number
  transactionHash: string
  safeTxHash: string
  executor?: string
  isExecuted: boolean
  isSuccessful?: boolean
  ethGasPrice?: string
  gasUsed?: number
  fee?: number
  origin: string
  dataDecoded?: string
  confirmationsRequired: number
  confirmations?: [
    {
      owner: string
      submissionDate: string
      transactionHash?: string
      confirmationType?: string
      signature: string
      signatureType?: string
    },
    // ...
  ]
  signatures?: string
}

7. Confirm/reject the transaction

The owners of the Safe can now sign the transaction obtained from the Safe Transaction Service by calling the method signTransactionHash from the Safe Core SDK to generate the signature and by calling the method confirmTransaction from the Safe Service Client to add the signature to the service.

// transaction: SafeMultisigTransactionResponse

const hash = transaction.safeTxHash
let signature = await safeSdk.signTransactionHash(hash)
await safeService.confirmTransaction(hash, signature.data)

8. Execute the transaction

Once there are enough confirmations in the service the transaction is ready to be executed. The account that will execute the transaction needs to retrieve it from the service with all the required signatures and call the method executeTransaction from the Safe Core SDK.

The method executeTransaction accepts an instance of the class SafeTransaction so the transaction needs to be transformed from the type SafeMultisigTransactionResponse.

import { EthSignSignature } from '@safe-global/safe-core-sdk'

// transaction: SafeMultisigTransactionResponse

const safeTransactionData: SafeTransactionData = {
  to: transaction.to,
  value: transaction.value,
  data: transaction.data,
  operation: transaction.operation,
  safeTxGas: transaction.safeTxGas,
  baseGas: transaction.baseGas,
  gasPrice: transaction.gasPrice,
  gasToken: transaction.gasToken,
  refundReceiver: transaction.refundReceiver,
  nonce: transaction.nonce
}
const safeTransaction = await safeSdk.createTransaction({ safeTransactionData })
transaction.confirmations.forEach(confirmation => {
  const signature = new EthSignSignature(confirmation.owner, confirmation.signature)
  safeTransaction.addSignature(signature)
})

const executeTxResponse = await safeSdk.executeTransaction(safeTransaction)
const receipt = executeTxResponse.transactionResponse && (await executeTxResponse.transactionResponse.wait())

Optionally, the isValidTransaction method, that returns a boolean value, could be called right before the executeTransaction method to check if the transaction will be executed successfully or not.

const isValidTx = await safeSdk.isValidTransaction(safeTransaction)

9. Interface checks

During the process of collecting the signatures/executing transactions, some useful checks can be made in the interface to display or hide a button to confirm or execute the transaction depending on the current number of confirmations, the address of accounts that confirmed the transaction and the Safe threshold:

Check if a Safe transaction is already signed by an owner:

const isTransactionSignedByAddress = (signerAddress: string, transaction: SafeMultisigTransactionResponse) => {
  const confirmation = transaction.confirmations.find(confirmation => confirmation.owner === signerAddress)
  return !!confirmation
}

Check if a Safe transaction is ready to be executed:

const isTransactionExecutable = (safeThreshold: number, transaction: SafeMultisigTransactionResponse) => {
  return transaction.confirmations.length >= safeThreshold
}

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integrating-the-safe-core-sdk.md

integrating-the-safe-core-sdk.md

Guide: Integrating the Safe Core SDK

Table of contents:

1. Install the dependencies

2. Initialize the SDK’s

Instantiate an EthAdapter

Initialize the Safe Service Client

Initialize the Safe Core SDK

3. Deploy a new Safe

4. Create a transaction

5. Propose the transaction to the service

6. Get the transaction from the service

7. Confirm/reject the transaction

8. Execute the transaction

9. Interface checks

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integrating-the-safe-core-sdk.md

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integrating-the-safe-core-sdk.md

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Guide: Integrating the Safe Core SDK

Table of contents:

Instantiate an EthAdapter

Initialize the Safe Service Client

Initialize the Safe Core SDK