Build a Web3 Wallet: Quick Start Guide with Wallet API and WaaS

Creating a Web3 wallet has never been easier, especially with modern Wallet-as-a-Service (WaaS) solutions and robust Web3 APIs. Whether you're building a decentralized application (dApp), managing digital assets at scale, or integrating blockchain functionality into your platform, mastering wallet creation, transaction handling, and data querying is essential. This guide walks you through the core steps of setting up a Web3 wallet using a secure and scalable API framework.

We'll cover everything from generating mnemonic phrases and addresses to creating accounts, building transactions, and monitoring on-chain activity — all powered by reliable wallet infrastructure.

Step 1: Generate Wallet Mnemonic and Address

To begin building your Web3 wallet, the first step is generating a secure mnemonic phrase and deriving blockchain addresses. This foundational process ensures cryptographic ownership and control over digital assets.

You can use the provided Signing SDK to create a mnemonic and generate corresponding public addresses across various blockchain networks.

👉 Discover how to integrate wallet creation seamlessly into your app

Install the Signing SDK via npm

Start by installing the latest version of the signing SDK. For example, if you're working with EVM-compatible chains like Ethereum or BSC:

npm install @okxweb3/sdk-name

Make sure to check for the most up-to-date package name in the official documentation.

Local Setup and Initialization

Clone the SDK repository from the source.
Run the build script to compile the necessary modules.
Initialize a wallet instance for your target network.

Here’s an example for creating an EVM-based wallet:

const { evmWallet } = require('@okxweb3/sdk');

// Generate a new mnemonic
const mnemonic = evmWallet.generateMnemonic();
console.log("Mnemonic:", mnemonic);

// Create wallet instance from mnemonic
const wallet = evmWallet.getWalletFromMnemonic(mnemonic);
console.log("Address:", wallet.getAddress());

This code generates a BIP-39 compliant 12-word mnemonic and derives the associated Ethereum-style address.

Explore the Open-Source Demo

An open-source demo application is available to help you visualize and test these functionalities in real time.

🔗 View live demo
📂 Get source code on GitHub

The demo showcases key features such as mnemonic generation, address derivation, transaction signing, and more — ideal for developers getting started with Web3 integration.

Step 2: Create a Wallet Account

Now that you’ve generated a mnemonic and derived an initial address, it’s time to organize your assets using wallet accounts.

Understanding Wallet Structure

In Web3 development, three key concepts define wallet architecture:

Wallet: The top-level entity controlled by a single mnemonic phrase.
Account: A logical grouping under BIP-44 standards; one wallet can have multiple accounts (e.g., “Personal,” “Business”).
Address: Each account holds one or more blockchain addresses — one per chain (e.g., Ethereum, Polygon, Bitcoin).

Using this hierarchy allows better asset management, improved security segmentation, and streamlined balance tracking.

Create a Wallet Account via API

Call the POST /api/v5/wallet/create-account endpoint to register a new account under your wallet. You can then associate multiple addresses across different blockchains with this single account.

For example:

{
  "mnemonic": "your twelve word phrase here",
  "chains": ["eth", "matic", "btc"]
}

This request creates an account and automatically derives addresses on Ethereum, Polygon, and Bitcoin networks.

Once created, you can:

Query token balances across all linked chains.
Retrieve unified transaction histories.
Manage permissions and access controls per account.

This aggregation capability is critical for enterprise-grade applications requiring multi-chain visibility.

Step 3: Build and Send Transactions

With your wallet and account set up, you're ready to perform on-chain operations.

Fetch Transaction Signing Data

Before constructing a transaction, gather required parameters by calling:

POST /api/v5/wallet/pre-transaction/sign-info

This returns essential details such as:

Gas price and limit (for EVM chains)
Nonce
Network ID
Estimated fee

These values ensure your transaction complies with current network conditions.

Validate Address and Construct Transaction

Always validate recipient addresses before proceeding. Use the SDK's built-in validation method:

const isValid = evmWallet.validateAddress("0x...");

Then build the transaction object:

const tx = {
  to: "0xRecipientAddress",
  value: "1000000000000000000", // 1 ETH
  gasLimit: "21000",
  gasPrice: "50000000000",
  nonce: 123
};

Sign it securely using the private key derived from your mnemonic:

const signedTx = await wallet.signTransaction(tx);

👉 Learn how to securely sign and broadcast transactions in production

Broadcast Transaction to Blockchain

Use the POST /api/v5/wallet/send-transaction API to broadcast the signed raw transaction to the network.

Upon success, you’ll receive a response containing:

{
  "txHash": "0xabc123...",
  "status": "sent"
}

Your transaction is now pending confirmation on-chain.

Step 4: Query Transaction Details

After broadcasting, monitor the status of your transaction using its hash.

Call the following endpoints:

GET /api/v5/wallet/transaction/detail?txHash=... – Get full transaction metadata.
GET /api/v5/wallet/order-id/transaction-list – Retrieve transactions linked to a specific order or account.

A successful query returns:

{
  "blockNumber": 19876543,
  "from": "0xSender",
  "to": "0xRecipient",
  "value": "1 ETH",
  "status": "confirmed"
}

Real-Time Updates with Webhooks

For high-frequency applications (e.g., exchanges, gaming platforms), polling isn’t efficient. Instead, subscribe to Webhook notifications to receive instant updates when transactions are confirmed, failed, or dropped.

Set up webhooks to receive events such as:

transaction.confirmed
balance.updated
withdrawal.completed

This enables real-time user experiences without unnecessary API calls.

Frequently Asked Questions (FAQ)

Q: Is my mnemonic stored on your servers?
A: No. The mnemonic is generated client-side and never transmitted or stored by the API provider. You retain full custody at all times.

Q: Can I manage non-EVM chains like Bitcoin or Solana?
A: Yes. The SDK supports multiple blockchain standards including UTXO-based (Bitcoin) and account-based (Solana, Cosmos) models.

Q: How do I handle gas fees dynamically?
A: Use the /pre-transaction/sign-info endpoint to fetch real-time gas estimates before signing any transaction.

Q: What happens if I lose my mnemonic?
A: There is no recovery mechanism. Always back up your mnemonic securely using hardware wallets or encrypted storage solutions.

Q: Are there rate limits on API usage?
A: Yes, but enterprise plans offer higher throughput and dedicated support. Check documentation for current thresholds.

Q: Can I use this in a mobile app?
A: Absolutely. The SDK is lightweight and compatible with React Native, Flutter, and other cross-platform frameworks.

Final Thoughts

By following these four steps — generating keys, creating accounts, sending transactions, and monitoring activity — you’ve laid the foundation for a fully functional Web3 wallet integrated with powerful backend APIs.

Modern Wallet-as-a-Service platforms eliminate much of the complexity traditionally associated with blockchain development. With secure key management, multi-chain support, and real-time data access, developers can focus on user experience rather than low-level cryptography.

👉 Start building your scalable Web3 wallet today

Whether you're launching a dApp, creating custodial solutions, or enabling payments in a metaverse environment, leveraging a robust Web3 API accelerates time-to-market while ensuring reliability and compliance.

Core Keywords: Web3 wallet, Wallet API, Wallet-as-a-Service (WaaS), blockchain transaction, mnemonic phrase, address generation, multi-chain wallet, signing SDK