@sw4p/bridge

The official TypeScript SDK for sw4p - gasless cross-chain transfers for stablecoins and native tokens across any blockchain.

Features

• 🔄 Cross-Chain Transfers - Move tokens between any supported blockchain
• ⛽ Gasless - Users don't need native tokens for gas
• 🔐 Non-Custodial - SDK never handles private keys
• ⚡ Fast - Transfers complete in ~60 seconds
• 🛠️ Simple API - 3 core methods: transfer(), estimateFee(), getStatus()
• 🌐 Extensible - Designed to support every blockchain and token

Installation

npm install @sw4p/bridge
# or
pnpm add @sw4p/bridge

Quick Start

import { Sw4pBridge } from '@sw4p/bridge'

const bridge = new Sw4pBridge({ apiKey: 'sk_...' })

// Estimate fees
const estimate = await bridge.estimateFee({
  from: 'BASE',
  to: 'SOLANA',
  amount: '100.00'
})
console.log(`Fee: $${estimate.fee.total}, Receive: $${estimate.netReceive}`)

// Execute transfer
const result = await bridge.transfer({
  from: 'BASE',
  to: 'SOLANA',
  amount: '100.00',
  recipient: '5abc...',
  permit: signedPermit
})

// Track status
const status = await bridge.getStatus(result.intentId)
// status.status: 'pending' | 'processing' | 'complete' | 'failed'

Solana → EVM Transfers

Solana source transfers use a two-step signing flow:

import { Sw4pBridge } from '@sw4p/bridge'
import { useWallet } from '@solana/wallet-adapter-react'

const bridge = new Sw4pBridge({ apiKey: 'sk_...' })
const { signTransaction } = useWallet()

// 1. Build transaction
const { transaction, intentId } = await bridge.createSolanaTransfer({
  to: 'BASE',
  amount: '100.00',
  fromWallet: publicKey.toBase58(),
  recipient: '0x...'
})

// 2. Sign with wallet
const tx = Transaction.from(Buffer.from(transaction, 'base64'))
const signed = await signTransaction(tx)

// 3. Submit
const result = await bridge.submitSolanaTransfer({
  intentId,
  signedTransaction: Buffer.from(signed.serialize()).toString('base64')
})

EVM Permit Signing

Create gasless approvals using EIP-2612 permits:

import { Sw4pBridge } from '@sw4p/bridge'
import { useSignTypedData } from 'wagmi'

const bridge = new Sw4pBridge({ apiKey: 'sk_...' })

// Create permit typed data
const permitData = bridge.createPermitTypedData({
  chain: 'BASE',
  owner: userAddress,
  spender: BRIDGE_SPENDER,
  value: parseUnits('100', 6),
  nonce: await getNonce()
})

// Sign with wallet
const signature = await signTypedData(permitData)

// Use in transfer
await bridge.transfer({ ...params, permit: parseSignature(signature) })

API Reference

Core Methods

| Method | Description | |--------|-------------| | transfer(params) | Execute cross-chain transfer | | estimateFee(params) | Get fee estimate before transfer | | getStatus(intentId) | Poll transfer status |

Route Helpers

| Method | Description | |--------|-------------| | supportsRoute(from, to) | Check if route is supported | | getSupportedPairs() | List all available routes | | getLimits() | Get min/max transfer amounts |

Signing Helpers

| Method | Description | |--------|-------------| | createPermitTypedData(params) | Generate EIP-712 permit data | | createSolanaTransfer(params) | Build Solana transaction for signing | | submitSolanaTransfer(params) | Submit signed Solana transaction |

Supported Chains (MVP)

Note: sw4p is designed to support every blockchain. Current MVP supports:

| Chain | Code | Type | |-------|------|------| | Ethereum | ETH | EVM | | Base | BASE | EVM | | Arbitrum | ARB | EVM | | Polygon | POLYGON | EVM | | Solana | SOLANA | Non-EVM |

Tokens: USDC (more tokens coming soon)

Error Handling

import { ApiError, AuthError, RateLimitError } from '@sw4p/bridge'

try {
  await bridge.transfer(params)
} catch (error) {
  if (error instanceof AuthError) {
    console.log('Invalid API key')
  } else if (error instanceof RateLimitError) {
    console.log(`Rate limited, retry in ${error.retryAfterMs}ms`)
  } else if (error instanceof ApiError) {
    console.log(`API error: ${error.message}`)
  }
}

Configuration

const bridge = new Sw4pBridge({
  apiKey: 'sk_...',           // Required
  baseUrl: 'https://...',     // Optional: custom API endpoint
  debug: true,                // Optional: enable request logging
  retry: {
    maxAttempts: 3,           // Retry failed requests
    backoffMs: 1000           // Initial backoff delay
  }
})

License

MIT