Skip to main content

WalletHelper API

Utilities for wallet and key management.

Import​

import { WalletHelper } from 'cardano-devkit';

generateSeed()​

Generate a new BIP-39 mnemonic seed phrase.

const seed = WalletHelper.generateSeed(wordCount);

Parameters​

  • wordCount?: 12 | 15 | 18 | 21 | 24 - Number of words (default: 24)

Returns​

string - Space-separated mnemonic words

Example​

// 24-word seed (default, most secure)
const seed24 = WalletHelper.generateSeed();
// "abandon abandon ... about"

// 12-word seed
const seed12 = WalletHelper.generateSeed(12);

validateSeed()​

Validate a BIP-39 mnemonic seed phrase.

const isValid = WalletHelper.validateSeed(seed);

Parameters​

  • seed: string - Mnemonic seed phrase

Returns​

boolean - True if valid

Example​

const valid = WalletHelper.validateSeed(
  "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about"
);
console.log(valid); // true

const invalid = WalletHelper.validateSeed("not a valid seed");
console.log(invalid); // false

seedToPrivateKey()​

Convert a seed phrase to a private key.

const privateKey = WalletHelper.seedToPrivateKey(seed);

Parameters​

  • seed: string - BIP-39 mnemonic seed phrase

Returns​

string - Ed25519 private key (bech32 encoded)

Example​

const seed = WalletHelper.generateSeed();
const privateKey = WalletHelper.seedToPrivateKey(seed);
// "ed25519_sk1..."

// Use with Lucid
lucid.selectWallet.fromPrivateKey(privateKey);

privateKeyToPublicKey()​

Derive a public key from a private key.

const publicKey = WalletHelper.privateKeyToPublicKey(privateKey);

Parameters​

  • privateKey: string - Ed25519 private key

Returns​

string - Ed25519 public key (bech32 encoded)

privateKeyToAddress()​

Derive an address from a private key.

const address = await WalletHelper.privateKeyToAddress(privateKey, network);

Parameters​

  • privateKey: string - Ed25519 private key
  • network: NetworkType - Target network

Returns​

Promise<string> - Bech32 address

Example​

const address = await WalletHelper.privateKeyToAddress(
  privateKey,
  'Preprod'
);
// "addr_test1qz..."

seedToAddress()​

Derive an address directly from a seed phrase.

const address = await WalletHelper.seedToAddress(seed, network);

Parameters​

  • seed: string - BIP-39 mnemonic seed phrase
  • network: NetworkType - Target network

Returns​

Promise<string> - Bech32 address

Example​

const seed = WalletHelper.generateSeed();
const address = await WalletHelper.seedToAddress(seed, 'Preprod');

createHDWallet()​

Create an HD wallet for deriving multiple addresses.

const hdWallet = WalletHelper.createHDWallet(seed);

Parameters​

  • seed: string - BIP-39 mnemonic seed phrase

Returns​

HDWallet instance

Example​

const hdWallet = WalletHelper.createHDWallet(seed);

// Derive addresses
const addr0 = await hdWallet.deriveAddress(0, 'Preprod');
const addr1 = await hdWallet.deriveAddress(1, 'Preprod');
const addr2 = await hdWallet.deriveAddress(2, 'Preprod');

formatLovelace()​

Format lovelace amount to ADA string.

const formatted = WalletHelper.formatLovelace(lovelace, decimals);

Parameters​

  • lovelace: bigint - Amount in lovelace
  • decimals?: number - Decimal places (default: 6)

Returns​

string - Formatted ADA amount

Example​

WalletHelper.formatLovelace(1_500_000n);
// "1.5"

WalletHelper.formatLovelace(1_500_000n, 2);
// "1.50"

WalletHelper.formatLovelace(1_234_567_890n);
// "1234.56789"

parseAda()​

Parse ADA string to lovelace.

const lovelace = WalletHelper.parseAda(ada);

Parameters​

  • ada: string | number - ADA amount

Returns​

bigint - Amount in lovelace

Example​

WalletHelper.parseAda('1.5');
// 1_500_000n

WalletHelper.parseAda(10);
// 10_000_000n

WalletHelper.parseAda('0.123456');
// 123_456n

Type Definitions​

HDWallet​

interface HDWallet {
  deriveAddress: (index: number, network: NetworkType) => Promise<string>;
  derivePrivateKey: (index: number) => string;
  derivePublicKey: (index: number) => string;
}

Usage Patterns​

Create and Fund a Wallet​

import { createDevKit, WalletHelper, createDevnetManager } from 'cardano-devkit';

// Generate wallet
const seed = WalletHelper.generateSeed();
console.log('Save this seed:', seed);

// Get address
const devKit = createDevKit({ network: 'LocalDevnet' });
const lucid = await devKit.init();
lucid.selectWallet.fromSeed(seed);
const address = await lucid.wallet().address();

// Fund on local devnet
const devnet = createDevnetManager();
await devnet.topup(address, 100_000_000n);

Multiple Accounts​

const seed = WalletHelper.generateSeed();
const hdWallet = WalletHelper.createHDWallet(seed);

// Create 5 addresses
const addresses = await Promise.all(
  [0, 1, 2, 3, 4].map(i => hdWallet.deriveAddress(i, 'Preprod'))
);

console.log('Addresses:', addresses);

Secure Key Handling​

// ✅ Good: Keep seeds in memory only when needed
async function signTransaction(seed: string, tx: Transaction) {
  const privateKey = WalletHelper.seedToPrivateKey(seed);
  lucid.selectWallet.fromPrivateKey(privateKey);
  const signed = await tx.sign.withWallet().complete();
  // privateKey goes out of scope
  return signed;
}

// ❌ Bad: Don't store seeds in plain text
localStorage.setItem('seed', seed); // Never do this!