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Documentation Index

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FuseBox is Fuse’s open-source Wallet-as-a-Service platform built on ERC-4337 account abstraction. It gives developers a Bundler to collect UserOperations and a Paymaster to sponsor gas fees, making it possible to deliver a completely gasless experience to end users. The platform is accessible via TypeScript and Flutter SDKs, and it connects directly to the Fuse blockchain without requiring a separate RPC node provider.

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What FuseBox provides

FuseBox is built on the FuseBox Backend, a NestJS service that exposes ERC-4337 smart contract infrastructure through a set of REST APIs and SDKs.

ERC-4337 smart accounts

Create programmable smart contract wallets for your users without manual onboarding.

Bundler

Collect and submit UserOperations to the network on behalf of your users.

Paymaster

Sponsor gas fees so users never need to hold FUSE tokens to transact.

SDKs

TypeScript (@fuseio/fusebox-web-sdk) and Flutter (Dart) SDKs for rapid integration.

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Prerequisites

Before creating an Operator account, make sure you have the following:
  • A working knowledge of the Fuse blockchain
  • A Web3 wallet such as MetaMask or Coinbase Wallet
  • FUSE tokens in your Externally Owned Account (EOA). You can purchase FUSE on the Console or bridge assets from another chain using the Bridge.
Gas fees on Fuse are very low. Sponsoring your users’ transactions via Paymaster is economical even at scale.

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Get an API key

1

Go to console.fuse.io

Navigate to console.fuse.io. You will see the Console welcome page.
2

Connect your wallet

Click Connect Wallet. You will be prompted to sign a message using MetaMask or Coinbase Wallet to verify ownership of your EOA. After signing, you are redirected to your Dashboard, which shows your FUSE token balance and the Wallet, Build, Bridge, and Staking menu items.
3

Become an Operator

Click Become an Operator. This redirects you to the Build section of the Console. Operator accounts are developer accounts that enable you to obtain an API key, fund a Paymaster, and pay for premium subscriptions in future updates. Operators can freely deposit and withdraw any token available on the Fuse network.
4

Create your project

Click Create your project on the Operator landing page. This opens the Operator dashboard.
5

Create an Operator Wallet

Click Create Operator Wallet. Your wallet provider will prompt you to sign a message. After signing, fill in your contact details and confirm. You will see a success screen confirming that your Operator account has been created.
Your Operator Account Address is a Smart Contract Wallet. It supports ERC-4337 functions including batch transaction requests.
6

Fund the Operator Account

Click Add funds and copy your Operator Account address. Send at least 10 FUSE tokens to this address.Once the balance is confirmed, your API key becomes accessible on the Operator dashboard.

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Set up Paymaster for gasless transactions

Your Operator account’s Paymaster is pre-funded with 1 FUSE when created. To activate gasless transactions in your application, pass withPaymaster: true as the third argument when initialising the FuseBox SDK: 
import { FuseSDK } from "@fuseio/fusebox-web-sdk";
import { ethers } from "ethers";

const apiKey = "YOUR_FUSEBOX_API_KEY";
const credentials = new ethers.Wallet(privateKey);

const fuseSDK = await FuseSDK.init(apiKey, credentials, {
  withPaymaster: true,
});
When withPaymaster is enabled, the Paymaster covers the gas cost of every UserOperation submitted through the SDK. Your Operator account balance is debited for those fees.
Monitor your Operator account balance on the Console. If the Paymaster balance is depleted, sponsored transactions will fail. Top up via the Add funds button.
Once initialised, you can call any FuseBox SDK method — token transfers, NFT transfers, contract calls, and more — and your users will never see a gas prompt. See the FuseBox SDK overview for the full list of available operations.

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