Dfns Typescript SDK (dfns/dfns-sdk-ts)

Dfns Typescript SDK

https://github.com/dfns/dfns-sdk-ts
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# Dfns Typescript SDK

The Dfns Typescript SDK provides a comprehensive interface for integrating with Dfns's MPC (Multi-Party Computation) wallet infrastructure. It enables developers to create and manage wallets, sign transactions, and interact with multiple blockchain networks while maintaining institutional-grade security through cryptographic request signing. The SDK supports both server-side (Node.js) and client-side (browser) applications, with specialized signers for WebAuthn passkeys, asymmetric keys, and React Native.

At its core, the SDK implements a challenge-response authentication flow where all state-changing requests must be cryptographically signed by registered credentials. This ensures that only authorized users can perform sensitive operations like creating wallets or signing transactions. The SDK provides platform-specific integrations for over 20 blockchain ecosystems including Ethereum, Bitcoin, Solana, and many others through dedicated library packages.

## DfnsApiClient - Main API Client

The `DfnsApiClient` is the primary interface for interacting with the Dfns API. It provides access to wallets, permissions, policies, webhooks, staking, and other Dfns services. All state-changing requests are automatically signed using the provided credential signer.

```typescript
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'

// Initialize the credential signer with your service account credentials
const signer = new AsymmetricKeySigner({
  credId: 'cr-6qs5v-kg7pc-xxxxxxxxxxxxxxxx',  // Credential ID from Dfns Dashboard
  privateKey: process.env.DFNS_PRIVATE_KEY!,  // PEM-formatted private key
})

// Create the API client
const dfnsClient = new DfnsApiClient({
  baseUrl: 'https://api.dfns.io',
  orgId: 'or-2ng9jv-80cfc-xxxxxxxxxxxxxxxx',  // Your organization ID
  authToken: process.env.DFNS_AUTH_TOKEN!,     // Service account or PAT token
  signer,
})

// Create a new Ethereum wallet
const wallet = await dfnsClient.wallets.createWallet({
  body: { network: 'EthereumSepolia' }
})
console.log('Created wallet:', wallet.id, wallet.address)
// Output: Created wallet: wa-3p1nb-xxxxxx 0x1234...abcd

// List all wallets
const { items: wallets } = await dfnsClient.wallets.listWallets({})
console.log(`Total wallets: ${wallets.length}`)

// Get wallet details with assets
const walletDetails = await dfnsClient.wallets.getWallet({ walletId: wallet.id })
const { assets } = await dfnsClient.wallets.getWalletAssets({ walletId: wallet.id })
console.log('Wallet assets:', assets)
```

## AsymmetricKeySigner - Server-Side Credential Signing

The `AsymmetricKeySigner` implements the `CredentialSigner` interface for server-side applications. It signs user action challenges using an asymmetric key pair (typically Ed25519 or ECDSA). This signer is used with service accounts or Personal Access Tokens (PATs).

```typescript
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'
import { DfnsApiClient } from '@dfns/sdk'

// The private key should be securely stored (e.g., environment variable, secrets manager)
const privateKeyPem = `-----BEGIN PRIVATE KEY-----
MC4CAQAwBQYDK2VwBCIEILpKMIKFoVZ4v1GWPn3y1R1VnMKbJ8HtR8k...
-----END PRIVATE KEY-----`

const signer = new AsymmetricKeySigner({
  credId: 'cr-6qs5v-kg7pc-xxxxxxxxxxxxxxxx',
  privateKey: privateKeyPem,
  algorithm: 'Ed25519'  // Optional: specify algorithm (defaults to key type detection)
})

// Use with DfnsApiClient for automatic request signing
const dfnsClient = new DfnsApiClient({
  baseUrl: 'https://api.dfns.io',
  orgId: 'or-2ng9jv-80cfc-xxxxxxxxxxxxxxxx',
  authToken: process.env.DFNS_AUTH_TOKEN!,
  signer,
})

// All state-changing operations are automatically signed
const signature = await dfnsClient.wallets.generateSignature({
  walletId: 'wa-3p1nb-xxxxxx',
  body: {
    kind: 'Hash',
    hash: '0xabcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890'
  }
})
console.log('Signature:', signature.signature?.r, signature.signature?.s)
```

## WebAuthnSigner - Browser-Side Passkey Authentication

The `WebAuthnSigner` enables passkey-based authentication in browser applications using WebAuthn (FIDO2). It implements both `CredentialSigner` and `CredentialStore` interfaces for signing challenges and creating new passkey credentials.

```typescript
import { WebAuthnSigner } from '@dfns/sdk-browser'
import { DfnsAuthenticator } from '@dfns/sdk'

// Initialize WebAuthn signer with your domain's relying party information
const webauthnSigner = new WebAuthnSigner({
  relyingParty: {
    id: 'acme.com',           // Use root domain for cross-subdomain passkey support
    name: 'Acme Corporation'  // Display name shown to users
  },
  timeout: 60000  // Optional: credential operation timeout in milliseconds
})

// User login with passkeys
const dfnsAuth = new DfnsAuthenticator({
  orgId: 'or-2ng9jv-80cfc-xxxxxxxxxxxxxxxx',
  baseUrl: 'https://api.dfns.io',
  signer: webauthnSigner,
})

// This triggers the browser's passkey prompt (TouchID, FaceID, etc.)
const { token } = await dfnsAuth.login({
  orgId: 'or-2ng9jv-80cfc-xxxxxxxxxxxxxxxx',
  username: 'user@example.com'
})
console.log('User authenticated, token:', token)

// User registration with new passkey
const registrationResult = await dfnsAuth.register({
  orgId: 'or-2ng9jv-80cfc-xxxxxxxxxxxxxxxx',
  username: 'newuser@example.com',
  registrationCode: 'reg-code-from-email'  // Registration code sent to user
})
console.log('User registered:', registrationResult.user.id)
```

## DfnsDelegatedApiClient - Delegated Signing Flow

The `DfnsDelegatedApiClient` enables server-initiated requests where the actual signing is delegated to the end user (typically in a browser). This is useful for web applications where the server orchestrates API calls but users sign with their own credentials.

```typescript
import { DfnsDelegatedApiClient } from '@dfns/sdk'
import { WebAuthnSigner } from '@dfns/sdk-browser'

// SERVER SIDE: Initialize delegated client with user's auth token
const delegatedClient = new DfnsDelegatedApiClient({
  baseUrl: 'https://api.dfns.io',
  orgId: 'or-2ng9jv-80cfc-xxxxxxxxxxxxxxxx',
  authToken: userAuthToken,  // Token from user's login session
})

// SERVER: Initiate wallet creation (returns challenge for user to sign)
const challenge = await delegatedClient.wallets.createWalletInit({
  body: { network: 'EthereumSepolia' }
})
// Send challenge to frontend...

// CLIENT SIDE: User signs the challenge with their passkey
const webauthnSigner = new WebAuthnSigner({
  relyingParty: { id: 'acme.com', name: 'Acme' }
})
const signedChallenge = await webauthnSigner.sign(challenge)
// Send signedChallenge back to server...

// SERVER: Complete the wallet creation with user's signed challenge
const wallet = await delegatedClient.wallets.createWalletComplete(
  { body: { network: 'EthereumSepolia' } },
  signedChallenge
)
console.log('Wallet created:', wallet.id)
```

## Wallets API - Create, Manage, and Sign

The Wallets API provides comprehensive wallet management including creation, listing, signing, transactions, and transfers. Wallets can be created for various blockchain networks with different key schemes.

```typescript
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'

const signer = new AsymmetricKeySigner({
  credId: process.env.DFNS_CRED_ID!,
  privateKey: process.env.DFNS_PRIVATE_KEY!,
})

const dfns = new DfnsApiClient({
  baseUrl: process.env.DFNS_API_URL!,
  orgId: process.env.DFNS_ORG_ID!,
  authToken: process.env.DFNS_AUTH_TOKEN!,
  signer,
})

// Create wallets for different networks
const ethWallet = await dfns.wallets.createWallet({
  body: { network: 'EthereumSepolia' }
})

const btcWallet = await dfns.wallets.createWallet({
  body: { network: 'BitcoinTestnet3' }
})

const solWallet = await dfns.wallets.createWallet({
  body: { network: 'SolanaDevnet' }
})

// Generate a signature (hash signing)
const hashSignature = await dfns.wallets.generateSignature({
  walletId: ethWallet.id,
  body: {
    kind: 'Hash',
    hash: '0x9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08'
  }
})
console.log('Hash signature:', hashSignature.signature)

// Generate a signature (message signing for EVM)
const messageSignature = await dfns.wallets.generateSignature({
  walletId: ethWallet.id,
  body: {
    kind: 'Message',
    message: '0x48656c6c6f20576f726c64'  // "Hello World" in hex
  }
})

// Generate EIP-712 typed data signature
const typedDataSignature = await dfns.wallets.generateSignature({
  walletId: ethWallet.id,
  body: {
    kind: 'Eip712',
    domain: {
      name: 'MyDApp',
      version: '1',
      chainId: 11155111,
      verifyingContract: '0x1234...'
    },
    types: {
      Message: [{ name: 'content', type: 'string' }]
    },
    message: { content: 'Hello' }
  }
})

// Broadcast a pre-signed transaction
const txResult = await dfns.wallets.broadcastTransaction({
  walletId: ethWallet.id,
  body: {
    kind: 'Evm',
    to: '0x1234567890123456789012345678901234567890',
    value: '1000000000000000',  // 0.001 ETH in wei
    data: '0x'
  }
})
console.log('Transaction ID:', txResult.id, 'Status:', txResult.status)

// Transfer assets
const transfer = await dfns.wallets.transferAsset({
  walletId: ethWallet.id,
  body: {
    kind: 'Native',
    to: '0x1234567890123456789012345678901234567890',
    amount: '1000000000000000'
  }
})

// Get wallet transaction history
const { items: history } = await dfns.wallets.getWalletHistory({
  walletId: ethWallet.id,
  query: { limit: '10' }
})
```

## Ethers.js Integration (v6)

The `@dfns/lib-ethersjs6` package provides a Dfns-backed signer compatible with ethers.js v6. It extends `AbstractSigner` and enables seamless integration with existing ethers.js code and dApps.

```typescript
import { DfnsWallet } from '@dfns/lib-ethersjs6'
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'
import { JsonRpcProvider, parseEther, Contract } from 'ethers'

// Initialize Dfns client
const signer = new AsymmetricKeySigner({
  credId: process.env.DFNS_CRED_ID!,
  privateKey: process.env.DFNS_PRIVATE_KEY!,
})

const dfnsClient = new DfnsApiClient({
  orgId: process.env.DFNS_ORG_ID!,
  authToken: process.env.DFNS_AUTH_TOKEN!,
  baseUrl: process.env.DFNS_API_URL!,
  signer,
})

// Initialize Dfns wallet (fetches wallet metadata)
const dfnsWallet = await DfnsWallet.init({
  walletId: process.env.ETHEREUM_WALLET_ID!,
  dfnsClient,
})

// Connect to Ethereum provider
const provider = new JsonRpcProvider('https://eth-sepolia.g.alchemy.com/v2/YOUR_KEY')
const wallet = dfnsWallet.connect(provider)

console.log('Wallet address:', await wallet.getAddress())

// Sign and send a transaction
const tx = await wallet.sendTransaction({
  to: '0x1234567890123456789012345678901234567890',
  value: parseEther('0.001'),
})
console.log('Transaction hash:', tx.hash)
await tx.wait()

// Sign a message
const signature = await wallet.signMessage('Hello, Dfns!')
console.log('Message signature:', signature)

// Interact with smart contracts
const ERC20_ABI = ['function transfer(address to, uint256 amount) returns (bool)']
const tokenContract = new Contract('0xTokenAddress...', ERC20_ABI, wallet)

const transferTx = await tokenContract.transfer(
  '0xRecipient...',
  parseEther('100')
)
await transferTx.wait()
```

## Viem Integration

The `@dfns/lib-viem` package provides a Dfns-backed wallet compatible with viem. It can be used with viem's `toAccount` to create a local account for signing operations.

```typescript
import { DfnsWallet } from '@dfns/lib-viem'
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'
import { createWalletClient, http, parseEther } from 'viem'
import { sepolia } from 'viem/chains'
import { toAccount } from 'viem/accounts'

// Initialize Dfns client
const signer = new AsymmetricKeySigner({
  credId: process.env.DFNS_CRED_ID!,
  privateKey: process.env.DFNS_PRIVATE_KEY!,
})

const dfnsClient = new DfnsApiClient({
  orgId: process.env.DFNS_ORG_ID!,
  authToken: process.env.DFNS_AUTH_TOKEN!,
  baseUrl: process.env.DFNS_API_URL!,
  signer,
})

// Initialize Dfns wallet
const dfnsWallet = await DfnsWallet.init({
  walletId: process.env.ETHEREUM_WALLET_ID!,
  dfnsClient,
})

console.log('Wallet address:', dfnsWallet.address)

// Create viem wallet client using Dfns wallet
const walletClient = createWalletClient({
  account: toAccount(dfnsWallet),
  chain: sepolia,
  transport: http('https://eth-sepolia.g.alchemy.com/v2/YOUR_KEY'),
})

// Send a transaction
const hash = await walletClient.sendTransaction({
  to: '0x1234567890123456789012345678901234567890',
  value: parseEther('0.001'),
})
console.log('Transaction hash:', hash)

// Sign a message
const messageSignature = await dfnsWallet.signMessage({
  message: 'Hello from Dfns!'
})
console.log('Message signature:', messageSignature)

// Sign typed data (EIP-712)
const typedSignature = await dfnsWallet.signTypedData({
  domain: {
    name: 'MyDApp',
    version: '1',
    chainId: 11155111,
  },
  types: {
    Message: [{ name: 'content', type: 'string' }],
  },
  primaryType: 'Message',
  message: { content: 'Hello' },
})
```

## Solana Integration

The `@dfns/lib-solana` package provides a Dfns-backed wallet for Solana, supporting both legacy and versioned transactions with the `@solana/web3.js` library.

```typescript
import { DfnsWallet } from '@dfns/lib-solana'
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'
import {
  Connection,
  PublicKey,
  SystemProgram,
  TransactionMessage,
  VersionedTransaction,
  clusterApiUrl,
} from '@solana/web3.js'

// Initialize Dfns client
const signer = new AsymmetricKeySigner({
  credId: process.env.DFNS_CRED_ID!,
  privateKey: process.env.DFNS_PRIVATE_KEY!,
})

const dfnsClient = new DfnsApiClient({
  orgId: process.env.DFNS_ORG_ID!,
  authToken: process.env.DFNS_AUTH_TOKEN!,
  baseUrl: process.env.DFNS_API_URL!,
  signer,
})

// Initialize Dfns wallet for Solana
const wallet = await DfnsWallet.init({
  walletId: process.env.SOLANA_WALLET_ID!,
  dfnsClient,
})

console.log('Solana address:', wallet.address)
console.log('Public key:', wallet.publicKey.toBase58())

// Connect to Solana network
const connection = new Connection(clusterApiUrl('devnet'), 'confirmed')
const balance = await connection.getBalance(wallet.publicKey)
console.log('Balance:', balance / 1e9, 'SOL')

// Create and sign a transfer transaction
const toAddress = new PublicKey('3U6stgsD1FmA7o3omUguritCU8iWmUM7Rs6KqAHHxHVZ')
const amount = 100000000 // 0.1 SOL in lamports

const latestBlockhash = await connection.getLatestBlockhash()

const message = new TransactionMessage({
  payerKey: wallet.publicKey,
  recentBlockhash: latestBlockhash.blockhash,
  instructions: [
    SystemProgram.transfer({
      fromPubkey: wallet.publicKey,
      toPubkey: toAddress,
      lamports: BigInt(amount),
    }),
  ],
}).compileToV0Message()

const transaction = new VersionedTransaction(message)
const signedTx = await wallet.signVersionedTransaction(transaction)

// Broadcast the transaction
const txid = await connection.sendRawTransaction(signedTx.serialize())
await connection.confirmTransaction({ signature: txid, ...latestBlockhash })
console.log('Transaction signature:', txid)
```

## Bitcoin Integration (BitcoinJS)

The `@dfns/lib-bitcoinjs` package enables Bitcoin transaction signing using Dfns wallets with the `bitcoinjs-lib` library.

```typescript
import { DfnsWallet } from '@dfns/lib-bitcoinjs'
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'
import { networks, payments, Psbt } from 'bitcoinjs-lib'

// Initialize Dfns client
const signer = new AsymmetricKeySigner({
  credId: process.env.DFNS_CRED_ID!,
  privateKey: process.env.DFNS_PRIVATE_KEY!,
})

const dfnsClient = new DfnsApiClient({
  orgId: process.env.DFNS_ORG_ID!,
  authToken: process.env.DFNS_AUTH_TOKEN!,
  baseUrl: process.env.DFNS_API_URL!,
  signer,
})

// Initialize Dfns Bitcoin wallet
const wallet = await DfnsWallet.init({
  walletId: process.env.BITCOIN_WALLET_ID!,
  dfnsClient,
})

const network = networks.testnet

// Derive the wallet address from public key
const { address } = payments.p2wpkh({ pubkey: wallet.publicKey, network })
console.log('Bitcoin address:', address)

// Create a PSBT (Partially Signed Bitcoin Transaction)
const psbt = new Psbt({ network })

// Add input (UTXO)
psbt.addInput({
  hash: '87872516c6e93f136fc6c493c7172596b11c695e27889de7532abffcac2a4b5e',
  index: 1,
  witnessUtxo: {
    script: Buffer.from('0014abc123...', 'hex'),  // scriptPubKey
    value: 50000,  // satoshis
  },
})

// Add outputs
const fee = 150
const sendAmount = 1000

psbt.addOutput({
  address: 'tb1q5s9xtdr07dk98ud0hr34ufdycz70exte2kehm2',  // Recipient
  value: sendAmount,
})

psbt.addOutput({
  address: address!,  // Change back to self
  value: 50000 - sendAmount - fee,
})

// Sign the PSBT with Dfns wallet
const signedPsbt = await wallet.SignPsbt(psbt)
const finalizedPsbt = signedPsbt.finalizeAllInputs()
const txHex = finalizedPsbt.extractTransaction().toHex()

console.log('Signed transaction hex:', txHex)
// Broadcast using Bitcoin node RPC or block explorer API
```

## BaseAuthApi - Authentication Endpoints

The `BaseAuthApi` provides static methods for authentication flows including login, registration, and recovery. These are lower-level APIs used by `DfnsAuthenticator` and can be used directly for custom authentication implementations.

```typescript
import { BaseAuthApi } from '@dfns/sdk/baseAuthApi'
import { WebAuthnSigner } from '@dfns/sdk-browser'

const apiOptions = {
  baseUrl: 'https://api.dfns.io',
  orgId: 'or-2ng9jv-80cfc-xxxxxxxxxxxxxxxx',
}

// User Login Flow
// Step 1: Create login challenge
const loginChallenge = await BaseAuthApi.createUserLoginChallenge({
  username: 'user@example.com',
  orgId: apiOptions.orgId,
}, apiOptions)

// Step 2: Sign challenge with WebAuthn
const webauthn = new WebAuthnSigner({
  relyingParty: { id: 'acme.com', name: 'Acme' }
})
const assertion = await webauthn.sign(loginChallenge)

// Step 3: Complete login
const { token } = await BaseAuthApi.createUserLogin({
  challengeIdentifier: loginChallenge.challengeIdentifier,
  firstFactor: assertion,
}, apiOptions)
console.log('Login successful, token:', token)

// User Registration Flow
// Step 1: Create registration challenge (requires registration code from invite)
const regChallenge = await BaseAuthApi.createUserRegistrationChallenge({
  orgId: apiOptions.orgId,
  username: 'newuser@example.com',
  registrationCode: 'reg-code-from-email',
}, apiOptions)

// Step 2: Create new passkey credential
const attestation = await webauthn.create(regChallenge)

// Step 3: Complete registration
const registration = await BaseAuthApi.createUserRegistration({
  firstFactorCredential: attestation,
}, {
  ...apiOptions,
  authToken: regChallenge.temporaryAuthenticationToken,
})
console.log('User registered:', registration.user.id)

// Logout
await BaseAuthApi.userLogout({
  ...apiOptions,
  authToken: token,
})
```

## Policies and Permissions API

The Policies and Permissions APIs enable fine-grained access control and approval workflows for wallet operations.

```typescript
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'

const dfns = new DfnsApiClient({
  baseUrl: process.env.DFNS_API_URL!,
  orgId: process.env.DFNS_ORG_ID!,
  authToken: process.env.DFNS_AUTH_TOKEN!,
  signer: new AsymmetricKeySigner({
    credId: process.env.DFNS_CRED_ID!,
    privateKey: process.env.DFNS_PRIVATE_KEY!,
  }),
})

// Create a policy requiring approval for large transfers
const policy = await dfns.policies.createPolicy({
  body: {
    name: 'Large Transfer Approval',
    activityKind: 'Wallets:TransferAsset',
    rule: {
      kind: 'TransferAmountLimit',
      configuration: {
        limit: '1000000000000000000',  // 1 ETH in wei
        currency: 'ETH',
      },
    },
    action: {
      kind: 'RequestApproval',
      approvalGroups: [
        {
          name: 'Finance Team',
          quorum: 2,  // Requires 2 approvals
          approvers: {
            userIds: ['us-xxx', 'us-yyy', 'us-zzz']
          }
        }
      ],
    },
    filters: {
      walletTags: ['production']  // Apply to wallets tagged 'production'
    }
  }
})
console.log('Policy created:', policy.id)

// List policies
const { items: policies } = await dfns.policies.listPolicies({})
console.log('Active policies:', policies.length)

// Create a permission (assign to user or service account)
const permission = await dfns.permissions.createPermission({
  body: {
    name: 'Wallet Reader',
    operations: ['Wallets:Read', 'Wallets:ReadSignature'],
  }
})

// Assign permission to users
await dfns.permissions.createPermissionAssignment({
  body: {
    permissionId: permission.id,
    identityId: 'us-user-id-xxx',
  }
})
```

## Webhooks API

The Webhooks API enables real-time notifications for wallet events like transactions, transfers, and policy approvals.

```typescript
import { DfnsApiClient } from '@dfns/sdk'
import { AsymmetricKeySigner } from '@dfns/sdk-keysigner'

const dfns = new DfnsApiClient({
  baseUrl: process.env.DFNS_API_URL!,
  orgId: process.env.DFNS_ORG_ID!,
  authToken: process.env.DFNS_AUTH_TOKEN!,
  signer: new AsymmetricKeySigner({
    credId: process.env.DFNS_CRED_ID!,
    privateKey: process.env.DFNS_PRIVATE_KEY!,
  }),
})

// Create a webhook for wallet events
const webhook = await dfns.webhooks.createWebhook({
  body: {
    url: 'https://your-server.com/webhooks/dfns',
    events: [
      'wallet.transfer.confirmed',
      'wallet.transaction.confirmed',
      'wallet.signature.signed',
      'policy.approval.pending',
    ],
    secret: 'your-webhook-secret-for-signature-verification',
  }
})
console.log('Webhook created:', webhook.id)

// List webhooks
const { items: webhooks } = await dfns.webhooks.listWebhooks({})

// Delete webhook
await dfns.webhooks.deleteWebhook({ webhookId: webhook.id })
```

## Summary

The Dfns Typescript SDK is designed for building secure, institutional-grade wallet infrastructure. The primary use cases include: (1) **Server-side automation** with service accounts using `AsymmetricKeySigner` for backend systems that manage wallets programmatically, (2) **User-facing applications** with `WebAuthnSigner` for web apps where users authenticate with passkeys, and (3) **Delegated flows** with `DfnsDelegatedApiClient` for hybrid architectures where servers orchestrate operations but users retain signing authority.

Integration patterns typically follow one of three approaches: Direct integration using `DfnsApiClient` for simple backend services, delegated integration for web applications that need user-controlled signing, or blockchain library integration (ethers.js, viem, Solana web3.js, etc.) for seamless dApp development. The SDK's modular architecture allows developers to import only the packages they need, with platform-specific integrations available for over 20 blockchain networks including Ethereum, Bitcoin, Solana, Cosmos, Polkadot, and many others.