Fast SDK and CLI Monorepo

Official TypeScript SDK and CLI for the Fast network.

What is Fast?

Fast is a next-generation payment network built for:

• AI agents — autonomous transactions, micropayments, and network operations
• High-frequency applications — sub-second finality, super high TPS (more than 100k)
• Cross-chain settlement — bridge tokens between Fast and EVM chains via AllSet
• HTTP-native payments — pay for API resources with the x402 protocol

This monorepo provides everything you need to build on Fast from TypeScript/Node.js.

Getting Started

Start with the CLI. It's the primary way to interact with the Fast network — all skill operations rely on it. Install it globally and use commands for accounts, balances, transfers, and x402 payments.

Use the SDK when you're building an integration. The SDK provides the Signer, FastProvider, and TransactionBuilder classes for programmatic control — useful for bots, AI agents, and custom workflows.

The monorepo contains multiple packages:

Package	What it's for
@fastxyz/cli	CLI tool — accounts, balances, sends, x402 payments
@fastxyz/sdk	Core SDK — signing, transactions, REST queries
@fastxyz/allset-sdk	AllSet SDK — bridge tokens between Fast and EVM
@fastxyz/x402-client	Pay for x402-protected HTTP resources
@fastxyz/x402-server	Protect API routes with x402 payments
@fastxyz/x402-facilitator	Verify and settle x402 payments on the network
@fastxyz/fast-schema	BCS/RPC/REST codec schemas
@fastxyz/x402-types	Shared x402 protocol types

Links

Resource	URL
@fastxyz/sdk	Core Fast SDK — signing, transactions, provider, conversions
@fastxyz/allset-sdk	AllSet SDK for bridge flows between Fast and EVM
@fastxyz/x402-client	Client SDK for paying for x402-protected resources
@fastxyz/x402-server	Server SDK for x402 payment verification / middleware
@fastxyz/x402-facilitator	Facilitator for verifying and settling x402 payments
@fastxyz/cli	CLI for account, network, balance, funding, send, and pay flows
@fastxyz/schema	Shared schema definitions for BCS, RPC, REST codecs, and types
@fastxyz/x402-types	Shared types and utilities for the x402 protocol

Quick Start

Which package do you need?

Package	When to use it
@fastxyz/cli	Terminal commands — accounts, balances, transfers, x402 payments
@fastxyz/sdk	Programmatic access — Signer, FastProvider, TransactionBuilder
@fastxyz/allset-sdk	Cross-chain bridging — EVM ↔ Fast via AllSet
@fastxyz/x402-client	Pay for 402-protected APIs (auto-handles HTTP 402)
@fastxyz/x402-server	Protect your API routes with payment requirements
@fastxyz/x402-facilitator	Run a payment verification/settlement service

Install the SDK

npm install @fastxyz/sdk

Build and Submit a Transaction

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

const signer = new Signer('abcdef0123456789...');
const provider = new FastProvider({ url: 'https://api.fast.xyz/proxy-rest' });

const account = await provider.getAccountInfo({
  address: await signer.getPublicKey(),
  tokenBalancesFilter: null,
  stateKeyFilter: null,
  certificateByNonce: null,
});

const envelope = await new TransactionBuilder({
  networkId: 'fast:mainnet',
  signer,
  nonce: account.nextNonce,
})
  .addBurn({ tokenId: '11'.repeat(32), amount: 100n })
  .sign();

await provider.submitTransaction(envelope);

For more details, see the @fastxyz/sdk README.

CLI

The Fast CLI provides command-line access to accounts, networks, transactions, and payments.

# Install globally
npm install -g @fastxyz/cli

# Or use via pnpm in the repo
pnpm cli --help

Common Commands

# Create an account
fast account create --name my-account

# List accounts
fast account list

# Check balance for the current/default account
fast info balance

# Send tokens on Fast
fast send fast1recipient... 1000 --token USDC

# Fund via fiat on-ramp
fast fund fiat --network mainnet

# Pay for x402-protected resource
fast pay https://api.example.com/protected

The CLI source lives in app/cli/. Run pnpm cli --help or pnpm cli <command> --help for the current command reference.

Development

This is a pnpm workspace monorepo.

# Install dependencies
pnpm install

# Build all packages
pnpm build

# Run tests
pnpm test

# Run CLI in development
pnpm cli --help

Package Overview

Core SDK

• @fastxyz/sdk — The main entry point for Fast network operations. Provides Signer, FastProvider, and TransactionBuilder for building, signing, and submitting transactions.

Cross-Chain (AllSet)

• @fastxyz/allset-sdk — Bridge tokens between Fast and EVM chains. Supports deposits (EVM → Fast) and withdrawals/intents (Fast → EVM).

x402 Payment Protocol

• @fastxyz/x402-client — Pay for HTTP resources protected by x402
• @fastxyz/x402-server — Server-side middleware to verify x402 payments
• @fastxyz/x402-facilitator — Settle and facilitate x402 payments

Shared Infrastructure

• @fastxyz/fast-schema — BCS encodings, RPC types, REST codecs
• @fastxyz/x402-types — Shared types for the x402 protocol

License

MIT