Polymarket Arbitrage Bot

Polymarket Arbitrage Bot

Skill by ara.so — Daily 2026 Skills collection.

TypeScript bot automating the dump-and-hedge strategy on Polymarket's 15-minute Up/Down markets (BTC, ETH, SOL, XRP). Detects sharp price drops, buys the dipped side, then hedges the opposite outcome when combined cost falls below a profit threshold.

Installation

git clone https://github.com/infraform/polymarket-arbitrage-bot.git
cd polymarket-arbitrage-bot
npm install
npm run build
cp .env.example .env

Key Commands

Always test with `npm run sim` before enabling production mode.

Project Structure

src/
├── main.ts            # Entry point, config load, market discovery, wiring
├── config.ts          # Loads/validates .env into typed config
├── api.ts             # Gamma + CLOB API client (markets, orderbook, orders, redemption)
├── monitor.ts         # Orderbook snapshot polling, strategy callback driver
├── dumpHedgeTrader.ts # Dump detection, leg1/leg2, stop-loss, P&L tracking
├── models.ts          # Shared types: Market, OrderBook, TokenPrice, etc.
└── logger.ts          # history.toml append log + stderr output

Environment Configuration

Create .env from .env.example:

# --- Wallet & Auth (required for production) ---
PRIVATE_KEY=0x_your_private_key_here
PROXY_WALLET_ADDRESS=0x_your_proxy_wallet_address
SIGNATURE_TYPE=2                        # 0=EOA, 1=Proxy, 2=GnosisSafe

# --- Optional explicit CLOB API credentials ---
# If not set, credentials are derived from signer automatically
API_KEY=
API_SECRET=
API_PASSPHRASE=

# --- API Endpoints (defaults are production Polymarket) ---
GAMMA_API_URL=https://gamma-api.polymarket.com
CLOB_API_URL=https://clob.polymarket.com

# --- Markets ---
MARKETS=btc                             # comma-separated: btc,eth,sol,xrp

# --- Polling ---
CHECK_INTERVAL_MS=1000
MARKET_CLOSURE_CHECK_INTERVAL_SECONDS=20

# --- Strategy Parameters ---
DUMP_HEDGE_SHARES=10                    # Shares per leg
DUMP_HEDGE_SUM_TARGET=0.95             # Hedge when leg1 + opposite_ask <= this
DUMP_HEDGE_MOVE_THRESHOLD=0.15         # 15% drop triggers dump detection
DUMP_HEDGE_WINDOW_MINUTES=2            # Watch window at period start
DUMP_HEDGE_STOP_LOSS_MAX_WAIT_MINUTES=5
DUMP_HEDGE_STOP_LOSS_PERCENTAGE=0.2

# --- Mode ---
PRODUCTION=false                        # true = real trades

Core Types (models.ts)

// Key shared types used throughout the bot
interface Market {
  conditionId: string;
  questionId: string;
  tokens: Token[];         // [upToken, downToken]
  startTime: number;
  endTime: number;
  asset: string;           // "BTC", "ETH", etc.
}

interface Token {
  tokenId: string;
  outcome: string;         // "Up" or "Down"
}

interface OrderBook {
  tokenId: string;
  outcome: string;
  bids: PriceLevel[];
  asks: PriceLevel[];
  bestBid: number;
  bestAsk: number;
}

interface TokenPrice {
  tokenId: string;
  outcome: string;
  bestBid: number;
  bestAsk: number;
  timestamp: number;
}

interface MarketSnapshot {
  upPrice: TokenPrice;
  downPrice: TokenPrice;
  timeRemainingSeconds: number;
  periodStart: number;
}

Strategy Flow

1. Discovery  → Gamma API finds current 15m market slug for each asset
2. Monitor    → Poll CLOB orderbooks every CHECK_INTERVAL_MS
3. Watch      → First DUMP_HEDGE_WINDOW_MINUTES: detect if ask drops >= MOVE_THRESHOLD
4. Leg 1      → Buy DUMP_HEDGE_SHARES of dumped side at current ask
5. Wait       → Watch for: leg1_entry + opposite_ask <= DUMP_HEDGE_SUM_TARGET
6. Leg 2      → Buy DUMP_HEDGE_SHARES of opposite outcome (hedge)
7. Stop-loss  → If hedge not triggered within STOP_LOSS_MAX_WAIT_MINUTES, hedge anyway
8. Rollover   → New 15m period → discover new market, reset state
9. Closure    → Redeem winning tokens (production), log P&L

Code Examples

Loading and using config (config.ts pattern)

import * as dotenv from 'dotenv';
dotenv.config();

interface BotConfig {
  privateKey: string;
  proxyWalletAddress: string | undefined;
  signatureType: number;
  markets: string[];
  production: boolean;
  checkIntervalMs: number;
  dumpHedgeShares: number;
  dumpHedgeSumTarget: number;
  dumpHedgeMoveThreshold: number;
  dumpHedgeWindowMinutes: number;
  stopLossMaxWaitMinutes: number;
  stopLossPercentage: number;
  gammaApiUrl: string;
  clobApiUrl: string;
}

function loadConfig(): BotConfig {
  return {
    privateKey: process.env.PRIVATE_KEY ?? '',
    proxyWalletAddress: process.env.PROXY_WALLET_ADDRESS,
    signatureType: parseInt(process.env.SIGNATURE_TYPE ?? '2'),
    markets: (process.env.MARKETS ?? 'btc').split(',').map(m => m.trim()),
    production: process.env.PRODUCTION === 'true',
    checkIntervalMs: parseInt(process.env.CHECK_INTERVAL_MS ?? '1000'),
    dumpHedgeShares: parseInt(process.env.DUMP_HEDGE_SHARES ?? '10'),
    dumpHedgeSumTarget: parseFloat(process.env.DUMP_HEDGE_SUM_TARGET ?? '0.95'),
    dumpHedgeMoveThreshold: parseFloat(process.env.DUMP_HEDGE_MOVE_THRESHOLD ?? '0.15'),
    dumpHedgeWindowMinutes: parseFloat(process.env.DUMP_HEDGE_WINDOW_MINUTES ?? '2'),
    stopLossMaxWaitMinutes: parseFloat(process.env.DUMP_HEDGE_STOP_LOSS_MAX_WAIT_MINUTES ?? '5'),
    stopLossPercentage: parseFloat(process.env.DUMP_HEDGE_STOP_LOSS_PERCENTAGE ?? '0.2'),
    gammaApiUrl: process.env.GAMMA_API_URL ?? 'https://gamma-api.polymarket.com',
    clobApiUrl: process.env.CLOB_API_URL ?? 'https://clob.polymarket.com',
  };
}

Fetching market via Gamma API (api.ts pattern)

import axios from 'axios';

// Find current 15m market for an asset
async function findCurrentMarket(
  gammaApiUrl: string,
  asset: string  // "btc", "eth", "sol", "xrp"
): Promise<Market | null> {
  // Polymarket 15m slug format: btc-updown-15m-<period_timestamp>
  // Round current time down to nearest 15m period
  const now = Math.floor(Date.now() / 1000);
  const periodStart = now - (now % (15 * 60));
  const slug = `${asset}-updown-15m-${periodStart}`;

  try {
    const response = await axios.get(`${gammaApiUrl}/markets`, {
      params: { slug }
    });
    const markets = response.data;
    if (!markets || markets.length === 0) return null;
    return markets[0] as Market;
  } catch (err) {
    console.error(`[${asset}] Market discovery failed:`, err);
    return null;
  }
}

Fetching orderbook from CLOB (api.ts pattern)

async function getOrderBook(
  clobApiUrl: string,
  tokenId: string
): Promise<OrderBook | null> {
  try {
    const response = await axios.get(`${clobApiUrl}/book`, {
      params: { token_id: tokenId }
    });
    const data = response.data;
    
    const bestBid = data.bids?.length > 0 
      ? Math.max(...data.bids.map((b: any) => parseFloat(b.price))) 
      : 0;
    const bestAsk = data.asks?.length > 0 
      ? Math.min(...data.asks.map((a: any) => parseFloat(a.price))) 
      : 1;
    
    return {
      tokenId,
      outcome: data.outcome ?? '',
      bids: data.bids ?? [],
      asks: data.asks ?? [],
      bestBid,
      bestAsk,
    };
  } catch (err) {
    console.error(`OrderBook fetch failed for ${tokenId}:`, err);
    return null;
  }
}

Dump detection logic (dumpHedgeTrader.ts pattern)

interface DumpHedgeState {
  phase: 'watching' | 'leg1_placed' | 'hedging' | 'closed';
  leg1Outcome?: 'Up' | 'Down';
  leg1EntryPrice?: number;
  leg1PlacedAt?: number;
  leg1TokenId?: string;
  hedgeTokenId?: string;
  periodStart: number;
}

function detectDump(
  snapshot: MarketSnapshot,
  priceHistory: TokenPrice[],
  config: BotConfig
): 'Up' | 'Down' | null {