Kaspa Swap SDK

A lightweight, headless swap SDK for Kaspa DeFi powered by Uniswap V2. Build your own UI and use the SDK to handle quotes, approvals, and swaps.

Examples

You can find some examples of how to use the SDK in the swap-sdk-examples repository.

Features

• 🔄 Token swapping with Uniswap V2 protocol
• 💰 Support for ERC-20 tokens and native Kaspa wrappers
• 🎛️ Headless controller: bring your own UI
• 🔌 Simple wallet integration (EIP-1193 providers)
• ⚡ Real-time quote calculations
• 🛡️ Slippage protection and deadlines

Installation

npm install @kaspacom/swap-sdk

Quick Start

Create the headless controller

import {
  createKaspaComSwapController,
  LoaderStatuses,
  Erc20Token,
} from 'swap-widget';

const controller = createKaspaComSwapController({
  networkConfig: 'kasplex-testnet',
  walletProvider: window.ethereum, // any EIP-1193 provider
  onChange: async (state, patch) => {
    console.log('state changed', patch, state);
    // Render your UI from state.computed, state.tradeInfo, state.loader, etc.
  },
});

Provide inputs and get a quote

const kas: Erc20Token = {
  address: '0x0000000000000000000000000000000000000000',
  symbol: 'KAS',
  name: 'Kaspa',
  decimals: 18,
};

const usdt: Erc20Token = {
  address: '0xD33d07ccfEd8038cEd1aa393FbEf7D7dA72be20e',
  symbol: 'USDT',
  name: 'Tether',
  decimals: 6,
};

await controller.setData({
  fromToken: kas,
  toToken: usdt,
  amount: 1.0,             // user-entered number
  isOutputAmount: false,    // false = amount is input; true = amount is desired output (How much the user will receive)
  settings: { maxSlippage: '0.5', swapDeadline: 20 },
});

// Quote results are in controller.getState().computed
const { computed } = controller.getState();
console.log('computed amounts', computed);

Connect wallet, approve if needed, and swap

await controller.connectWallet();

// Optional: call approve explicitly
await controller.approveIfNeeded();

// Perform the swap
const txHash = await controller.swap();
console.log('Swap TX hash:', txHash);

Load tokens from the subgraph (for token pickers)

const tokens = await controller.getTokensFromGraph(100, 'kas');
console.log(tokens);

API Reference

createKaspaComSwapController(options)

Creates and returns a SwapSdkController instance. Accepts either a preset string for networkConfig or a full SwapSdkNetworkConfig object.

• options.networkConfig: 'kasplex-testnet' or SwapSdkNetworkConfig
• options.walletProvider: EIP-1193 provider (e.g., window.ethereum)
• options.partnerKey?: Optional partner key string
• options.onChange?: (state, patch) => Promise<void> callback invoked on any state change

Returns: SwapSdkController

class SwapSdkController

• constructor(options: SwapSdkOptions): Normally use the factory createKaspaComSwapController.
• connectWallet(injectedProvider?: Eip1193Provider): Promise
  • Connects the wallet and sets signer on the swap service.
  • Returns the connected address.
• disconnectWallet(): void
  • Disconnects the wallet and clears signer.
• getState(): SwapControllerOutput
  • Returns the current controller state.
• setData(input: Partial): Promise
  • Merges provided input, triggers a quote calculation if possible, and returns updated state.
• calculateQuoteIfNeeded(): Promise
  • Re-calculates quote if fromToken, toToken, and amount are valid.
• approveIfNeeded(): Promise<string | undefined>
  • If allowance is insufficient, submits approval transaction and waits for confirmation.
  • Returns approval transaction hash when submitted, otherwise undefined if already approved.
• swap(): Promise
  • Executes the swap using last computed trade info and amounts. Returns swap transaction hash.
• getPartnerFee(): Promise
  • Fetches the current partner fee in percentage (bps/divisor).
• getTokensFromGraph(limit?: number, search?: string): Promise<any[]>
  • Queries the subgraph for tokens. Use for token lists/search.

Types

All types are exported from swap-widget.

• Erc20Token

  • address: string
  • symbol: string
  • name: string
  • decimals: number

• SwapSettings

  • maxSlippage: string (e.g., '0.5' for 0.5%)
  • swapDeadline: number (minutes)

• SwapSdkOptions

  • networkConfig: SwapSdkNetworkConfig | string
  • walletProvider: any (EIP-1193)
  • partnerKey?: string
  • onChange?: (state: SwapControllerOutput, patch: Partial<SwapControllerOutput>) => Promise<void>

• SwapControllerInput (used with setData)

  • fromToken?: Erc20Token | null
  • toToken?: Erc20Token | null
  • amount?: number (user-entered number)
  • isOutputAmount?: boolean (false = amount is input; true = amount is desired output)
  • settings?: Partial<SwapSettings>

• LoaderStatuses

  • CALCULATING_QUOTE = 1
  • APPROVING = 2
  • SWAPPING = 3

• ComputedAmounts (found in SwapControllerOutput.computed)

  • amountIn: string
    The input amount as entered by the user, formatted for display.

  • amountOut: string
    The output amount as calculated for the user, formatted for display.

  • amountInRaw: string
    The exact input amount (in smallest token units, e.g. wei) that will be sent to the swap contract.

  • amountOutRaw: string
    The exact output amount (in smallest token units, e.g. wei) that will be received from the swap contract.

  • maxAmountIn?: string
    (Optional) The maximum input amount the user need to send to receive the desired output amount. Only present if isOutputAmount is true.

  • minAmountOut?: string
    (Optional) The minimum output amount the user will receive, accounting for slippage. Only present if isOutputAmount is false.

  • maxAmountInRaw?: string
    (Optional) The raw (smallest units) value of maxAmountIn.

  • minAmountOutRaw?: string
    (Optional) The raw (smallest units) value of minAmountOut.

• SwapControllerOutput

  • error?: string
  • txHash?: string (Swap tx hash)
  • approveTxHash?: string (Approval transaction tx hash)
  • tradeInfo?: Trade<Currency, Currency, TradeType> (Uniswap V2 trade)
  • computed?: ComputedAmounts
  • loader: LoaderStatuses | null

• SwapSdkNetworkConfig (also see presets in NETWORKS)

  • name: string
  • chainId: number
  • rpcUrl: string
  • routerAddress: string
  • factoryAddress: string
  • proxyAddress?: string
  • graphEndpoint: string
  • blockExplorerUrl?: string
  • additionalJsonRpcApiProviderOptionsOptions?: any
  • nativeToken: Erc20Token
    The native token of the network (KAS).
  • wrappedToken: Erc20Token
    The wrapped native token (WKAS).

• NETWORKS

  • Preset map of network keys to SwapSdkNetworkConfig objects. Includes 'kasplex-testnet'.

Usage Patterns

• Exact input vs exact output
  • Set isOutputAmount to false to quote "sell X get best Y".
  • Set isOutputAmount to true to quote "get exactly X spend up to Y".
• React integration
  • Call setData on input changes; render from controller.getState().
  • Use state.loader to show spinners: LoaderStatuses.CALCULATING_QUOTE, APPROVING, SWAPPING.

Development

git clone https://github.com/kaspacom/swap-widget.git
cd swap-widget
npm install
npm run build

License

MIT License - see LICENSE.

Support

• Open an issue on GitHub
• Join our Telegram: https://t.me/KaspaComOfficial