Fast SDK

Official TypeScript SDK for the Fast network. Build wallets, send tokens, check balances, sign messages, and interact with Fast in Node.js applications.

Install

npm install @fastxyz/sdk

Quick Start

import { FastProvider, FastWallet } from '@fastxyz/sdk';

// Create provider (read-only connection)
const provider = new FastProvider({ network: 'testnet' });

// Create or load wallet
const wallet = await FastWallet.fromKeyfile('~/.fast/keys/default.json', provider);

// Check balance
const balance = await wallet.balance();
console.log(balance);

// Send tokens
const tx = await wallet.send({
  to: 'fast1...',
  amount: '1.0',
});
console.log(tx.txHash);

Architecture

The SDK uses a Provider/Wallet separation:

• FastProvider — Read-only connection to the Fast network. No private key needed.
• FastWallet — Wallet for signing transactions. Requires a provider.

Read-only operations (no key needed)

const provider = new FastProvider({ network: 'testnet' });
const balance = await provider.getBalance('fast1...');
const tokenInfo = await provider.getTokenInfo('fastUSDC');

Signing operations (key required)

const provider = new FastProvider({ network: 'testnet' });
const wallet = await FastWallet.fromKeyfile('~/.fast/keys/default.json', provider);
await wallet.send({ to: 'fast1...', amount: '10' });

Features

• Wallet Management - Create, load, or generate Fast wallets
• Token Operations - Send FAST, fastUSDC, or any Fast token
• Balance Queries - Check native and token balances
• Message Signing - Sign and verify messages with Ed25519
• Token Metadata - Look up token info and list holdings
• Protocol Compatibility - Submit transactions using the current VersionedTransaction::Release20260303 FastSet envelope automatically

Configuration

Network and token configuration is loaded from JSON files:

• Bundled defaults: src/data/networks.json, src/data/tokens.json
• User overrides: ~/.fast/networks.json, ~/.fast/tokens.json

User overrides take precedence over bundled defaults. Pass network: 'your-network-name' to FastProvider for any key defined in ~/.fast/networks.json.

Documentation

See SKILL.md for detailed API documentation and usage examples.

Development

npm install
npm run build
npm test

Releasing

See RELEASING.md for the npm release workflow.

License

MIT