> ## Documentation Index
> Fetch the complete documentation index at: https://sequence-0fb8d9e6-api_docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Connect and send transactions

> Learn how to integrate Sequence with your backend services

## Prerequisites

Before getting started, ensure you have:

* A Sequence project with an access key from [Sequence Builder](https://sequence.build)
* Node.js environment
* Required packages installed:

```bash theme={null}
npm install @0xsequence/auth @0xsequence/network ethers
```

### Setting Up the Provider

First, create a provider to connect to the blockchain:

Get your Sequence RPC URL from the [Sequence Builder](https://sequence.build).

```typescript theme={null}
import { findSupportedNetwork } from "@0xsequence/network";
import type { NetworkConfig } from "@0xsequence/network";
import { ethers } from "ethers";

export const getProvider = async (chainConfig: NetworkConfig) => {
    const provider = new ethers.JsonRpcProvider(process.env.SEQUENCE_RPC_URL, chainConfig.chainId);
    return provider;
};
```

### Signer Options

Sequence supports multiple signer types for secure key management.

#### 1. Raw Private Key Signer

This is the most basic signer type. It uses an ethers.Wallet instance to sign transactions.

```typescript theme={null}
import { Session } from "@0xsequence/auth";
import { findSupportedNetwork } from "@0xsequence/network";
import { ethers } from "ethers";

export const getLocalSigner = async (chainHandle: string) => {
    const chainConfig = findSupportedNetwork(chainHandle);
    if (!chainConfig) {
        throw new Error(`Chain config not found for chain handle: ${chainHandle}`);
    }

    const provider = await getProvider(chainConfig);
    const walletEOA = new ethers.Wallet(process.env.EVM_PRIVATE_KEY ?? '', provider);
    
    const smartAccount = await Session.singleSigner({
        signer: walletEOA,
        projectAccessKey: process.env.PROJECT_ACCESS_KEY ?? ''
    });

    return smartAccount.account.getSigner(chainConfig.chainId);
};
```

#### 2. Google Cloud KMS Signer

You can use Google Cloud KMS to securely manage your private keys.

<Steps>
  <Step>
    First install the `@0xsequence/google-kms-signer` package:

    ```bash theme={null}
    npm install @0xsequence/google-kms-signer
    ```
  </Step>

  <Step>
    You need to setup GCP KMS to get the required env variables.
    See a guide based on our Sidekick solution [here](https://docs.sequence.xyz/solutions/infrastructure/sidekick/overview#:~:text=GCP-,KMS,-Configuration%3A)
  </Step>

  <Step>
    Then, create a Google Cloud KMS signer:

    ```typescript theme={null}
    import { GoogleKmsSigner } from "@0xsequence/google-kms-signer";
    import { findSupportedNetwork } from "@0xsequence/network";

    export const getGoogleKmsSigner = async (chainHandle: string) => {
        const chainConfig = findSupportedNetwork(chainHandle);
        if (!chainConfig) {
            throw new Error(`Chain config not found for chain handle: ${chainHandle}`);
        }

        const googleKmsSigner = new GoogleKmsSigner({
            project: process.env.PROJECT ?? '',
            location: process.env.LOCATION ?? '',
            keyRing: process.env.KEY_RING ?? '',
            cryptoKey: process.env.CRYPTO_KEY ?? '',
            cryptoKeyVersion: process.env.CRYPTO_KEY_VERSION ?? ''
        });

        const smartAccount = await Session.singleSigner({
            signer: googleKmsSigner,
            projectAccessKey: process.env.PROJECT_ACCESS_KEY ?? ''
        });

        return smartAccount.account.getSigner(chainConfig.chainId);
    };
    ```
  </Step>
</Steps>

#### 3. AWS KMS Signer

You can use AWS KMS to securely manage your private keys.

<Steps>
  <Step>
    First install the `@0xsequence/aws-kms-signer` package:

    ```bash theme={null}
    npm install @0xsequence/aws-kms-signer
    ```
  </Step>

  <Step>
    You need to setup AWS KMS to get the required env variables.
    See a guide based on our Sidekick solution [here](https://docs.sequence.xyz/solutions/infrastructure/sidekick/overview#:~:text=AWS-,KMS,-Configuration%3A)
  </Step>

  <Step>
    Then, create an AWS KMS signer:

    ```typescript theme={null}
    export const getAwsKmsSigner = async (chainHandle: string) => {
        const chainConfig = findSupportedNetwork(chainHandle);
        if (!chainConfig) {
            throw new Error(`Chain config not found for chain handle: ${chainHandle}`);
        }

        const awsKmsSigner = new AwsKmsSigner(
            process.env.AWS_REGION ?? '',
            process.env.AWS_KMS_KEY_ID ?? ''
        );

        const smartAccount = await Session.singleSigner({
            signer: awsKmsSigner,
            projectAccessKey: process.env.PROJECT_ACCESS_KEY ?? ''
        });

        return smartAccount.account.getSigner(chainConfig.chainId);
    };
    ```
  </Step>
</Steps>

### Factory Pattern for Signer Selection

You can create a factory function to select the appropriate signer based on environment configuration:

```typescript theme={null}
export const getSigner = async (chainHandle: string) => {
    if (process.env.SIGNER_TYPE === 'google_kms') { 
        return getGoogleKmsSigner(chainHandle);
    } 
    if (process.env.SIGNER_TYPE === 'aws_kms') {
        return getAwsKmsSigner(chainHandle);
    }
    // Default to local signer
    return getLocalSigner(chainHandle);
};
```

If you want to learn more about the KMS Signer libraries, you can read our blog post [here](https://labs.sequence.xyz/secure-backend-wallets-cloud-kms/).

## Sending Transactions

Once you have a signer, you can use it to send transactions.

```typescript theme={null}
import { getSigner } from "./signer";

async function sendTransaction(chainId: string, to: string, value: string, data: string) {
    // Get the signer for the specified chain
    const signer = await getSigner(chainId);
    
    // Send the transaction
    const tx = await signer.sendTransaction({ to, value, data });
    
    // Wait for the transaction to be mined
    const receipt = await tx.wait();
    
    if (receipt?.status === 0) {
        throw new Error('Transaction reverted');
    }
    
    return {
        txHash: receipt?.hash,
        contractAddress: receipt?.contractAddress,
        txUrl: `https://${chainId}.etherscan.io/tx/${receipt?.hash}`
    };
}

async function sendTransactionBatch(chainId: string, transactions: { to: string, value: string, data: string }[]) {
    // Get the signer for the specified chain
    const signer = await getSigner(chainId);
    
    // Send the transaction batch
    const tx = await signer.sendTransaction(transactions);
    
    // Wait for the transaction to be mined
    const receipt = await tx.wait();
    
    if (receipt?.status === 0) {
        throw new Error('Transaction reverted');
    }
    
    return {
        txHash: receipt?.hash,
        contractAddress: receipt?.contractAddress,
        txUrl: `https://${chainId}.etherscan.io/tx/${receipt?.hash}`
    };
}
```

With this setup, you can securely connect to multiple blockchain networks and perform transactions from your backend services using Sequence.