Polymarket Copy Trading Bot

Skill by ara.so — Daily 2026 Skills collection.

A TypeScript bot that continuously monitors a target Polymarket wallet, detects trades in real time via REST polling and/or WebSocket, and mirrors BUY orders to your own account using the Polymarket CLOB SDK on Polygon mainnet.

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What It Does

• Monitors a target wallet via Polymarket Data API (REST polling every ~2s) and optionally WebSocket
• Mirrors BUY trades only — SELL trades are detected but skipped by default
• Sizes copies using a configurable POSITION_MULTIPLIER (default 10%) with min/max caps
• Submits orders as FOK, FAK, or LIMIT via the Polymarket CLOB client
• Enforces risk limits — per-session and per-market notional caps
• Supports three auth modes — EOA (SIG_TYPE=0), Poly Proxy (SIG_TYPE=1), Poly Polymorphic (SIG_TYPE=2)

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Installation

git clone https://github.com/Neron888/Polymarket-copy-trading-bot.git
cd Polymarket-copy-trading-bot
npm install

Requires Node.js v18+. The CLOB SDK requires ethers v5 (already pinned in package.json).

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Configuration

cp .env.example .env

Edit .env:

# Required
TARGET_WALLET=0xTargetWalletAddressToMonitor
WALLET_PRIVATE_KEY=0xYourPrivateKey
RPC_URL=https://your-quicknode-polygon-endpoint.quiknode.pro/your-key/

# Auth mode (0=EOA default, 1=Poly Proxy, 2=Poly Polymorphic)
SIG_TYPE=0
# Required only for SIG_TYPE=1 or 2
PROXY_WALLET_ADDRESS=

# Sizing
POSITION_MULTIPLIER=0.1      # 10% of target's trade size
MAX_TRADE_SIZE=100            # Max USDC per copied trade
MIN_TRADE_SIZE=1              # Min USDC per copied trade

# Order behavior
ORDER_TYPE=FOK                # FOK | FAK | LIMIT
SLIPPAGE_TOLERANCE=0.02       # 2%

# Risk caps (0 = disabled)
MAX_SESSION_NOTIONAL=500      # Total USDC for entire session
MAX_PER_MARKET_NOTIONAL=100   # Per market USDC cap

# Monitoring
USE_WEBSOCKET=true
POLL_INTERVAL=2000            # ms between REST polls
USE_USER_CHANNEL=false        # true = user WS channel, false = market channel

# Optional
POLYMARKET_GEO_TOKEN=
WS_ASSET_IDS=                 # comma-separated asset IDs for market WS
WS_MARKET_IDS=                # comma-separated condition IDs for user channel
MIN_PRIORITY_FEE_GWEI=30
MIN_MAX_FEE_GWEI=60

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Key Commands

# Start the bot (development mode with ts-node)
npm start

# Generate and persist API credentials to .polymarket-api-creds
npm run generate-api-creds

# Validate existing API credentials
npm run test-api-creds

# Compile TypeScript to dist/
npm run build

# Run compiled production build
npm run start:prod

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Architecture Overview

index.ts
  └── TradeMonitor      — REST polls Polymarket Data API for new target trades
  └── WebSocketMonitor  — Optional low-latency WS subscription (market or user channel)
  └── TradeExecutor     — Sizes trade, checks balance/allowance, submits CLOB order
  └── PositionTracker   — In-memory positions updated on fills
  └── RiskManager       — Session + per-market notional enforcement

Execution flow:

detect trade → BUY? → subscribe WS if needed → compute copy size
  → risk check → execute order (FOK/FAK/LIMIT) → record fill → update stats

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Code Examples

Starting the bot programmatically

import { startBot } from './src/index';

// The bot reads all config from process.env / .env
startBot();

TradeMonitor — polling pattern

import { TradeMonitor } from './src/TradeMonitor';

const monitor = new TradeMonitor({
  targetWallet: process.env.TARGET_WALLET!,
  pollInterval: Number(process.env.POLL_INTERVAL ?? 2000),
});

monitor.on('trade', (trade) => {
  console.log('New trade detected:', trade);
  // trade.side: 'BUY' | 'SELL'
  // trade.asset: token ID (outcome token address)
  // trade.size: USDC size
  // trade.price: fill price (0–1)
});

monitor.start();

TradeExecutor — placing a copy order

import { TradeExecutor } from './src/TradeExecutor';
import { ClobClient } from '@polymarket/clob-client';
import { ethers } from 'ethers';

const provider = new ethers.providers.JsonRpcProvider(process.env.RPC_URL);
const signer = new ethers.Wallet(process.env.WALLET_PRIVATE_KEY!, provider);

const clobClient = new ClobClient(
  'https://clob.polymarket.com',
  137, // Polygon chainId
  signer,
  apiCreds,          // loaded from .polymarket-api-creds
  Number(process.env.SIG_TYPE ?? 0),
  process.env.PROXY_WALLET_ADDRESS || undefined,
);

const executor = new TradeExecutor({
  client: clobClient,
  positionMultiplier: Number(process.env.POSITION_MULTIPLIER ?? 0.1),
  maxTradeSize: Number(process.env.MAX_TRADE_SIZE ?? 100),
  minTradeSize: Number(process.env.MIN_TRADE_SIZE ?? 1),
  orderType: (process.env.ORDER_TYPE ?? 'FOK') as 'FOK' | 'FAK' | 'LIMIT',
  slippageTolerance: Number(process.env.SLIPPAGE_TOLERANCE ?? 0.02),
});

// Copy a detected trade
await executor.copyTrade({
  side: 'BUY',
  tokenId: '0xAssetId...',
  originalSize: 12.5,   // USDC from target's trade
  price: 0.62,
});

RiskManager — checking before execution

import { RiskManager } from './src/RiskManager';

const riskManager = new RiskManager({
  maxSessionNotional: Number(process.env.MAX_SESSION_NOTIONAL ?? 0),
  maxPerMarketNotional: Number(process.env.MAX_PER_MARKET_NOTIONAL ?? 0),
});

const allowed = riskManager.checkTrade({
  marketId: '0xConditionId...',
  notional: copySize,
});

if (!allowed) {
  console.log('Trade blocked by risk limits');
}

WebSocket monitor — low-latency subscription

import { WebSocketMonitor } from './src/WebSocketMonitor';

const wsMonitor = new WebSocketMonitor({
  useUserChannel: process.env.USE_USER_CHANNEL === 'true',
  assetIds: process.env.WS_ASSET_IDS?.split(',').filter(Boolean) ?? [],
  marketIds: process.env.WS_MARKET_IDS?.split(',').filter(Boolean) ?? [],
});

wsMonitor.on('orderFilled', (fill) => {
  console.log('Fill received via WS:', fill);
});

wsMonitor.connect();

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Authentication Modes

EOA (default — SIG_TYPE=0)

SIG_TYPE=0
WALLET_PRIVATE_KEY=0xYourKey
# PROXY_WALLET_ADDRESS — leave empty

On first run, the bot auto-submits USDC.e/CTF approval transactions. Wallet needs POL for gas.

Poly Proxy (SIG_TYPE=1)

SIG_TYPE=1
WALLET_PRIVATE_KEY=0xSignerKey
PROXY_WALLET_ADDRESS=0xYourPolymarketProxyAddress

Poly Polymorphic (SIG_TYPE=2)

SIG_TYPE=2
WALLET_PRIVATE_KEY=0xSignerKey
PROXY_WALLET_ADDRESS=0xYourPolymorphicSafeAddress

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Generating API Credentials

npm run generate-api-creds

This derives API keys from your wallet signature and writes them to .polymarket-api-creds. Run once before npm start if you want to pre-generate credentials. The bot also auto-generates them on first start in EOA mode.

Validate credentials:

npm run test-api-creds

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Common Patterns

Conservative testing setup

POSITION_MULTIPLIER=0.05
MAX_TRADE_SIZE=5
MIN_TRADE_SIZE=1
MAX_SESSION_NOTIONAL=20
ORDER_TYPE=FOK
USE_WEBSOCKET=false

WebSocket-only market channel (lower latency)

USE_WEBSOCKET=true
USE_USER_CHANNEL=false
WS_ASSET_IDS=0xTokenId1,0xTokenId2

LIMIT orders with slippage buffer

ORDER_TYPE=LIMIT
SLIPPAGE_TOLERANCE=0.03

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Troubleshooting

Bot starts but no trades detected

• Verify TARGET_WALLET is a valid Polymarket wallet with recent activity
• Check POLL_INTERVAL — default 2000ms; lower means more API calls
• Confirm the target wallet trades on Polymarket (not just holds positions)

ethers version conflicts

• The project pins ethers v5. Do not upgrade to v6 — the CLOB SDK requires v5
• Run npm ls ethers to check for duplicate versions

Approval transactions failing

• Ensure the wallet has sufficient POL (MATIC) for gas on Polygon mainnet
• Try increasing MIN_PRIORITY_FEE_GWEI and MIN_MAX_FEE_GWEI if transactions stall

generate-api-creds fails

• Confirm WALLET_PRIVATE_KEY is correct and 0x-prefixed
• For SIG_TYPE=1/2, ensure PROXY_WALLET_ADDRESS matches your Polymarket account

Orders rejected by CLOB

• FOK orders fail if insufficient liquidity — try ORDER_TYPE=FAK or LIMIT
• Check SLIPPAGE_TOLERANCE isn't too tight for illiquid markets

Session notional cap hit immediately

• MAX_SESSION_NOTIONAL resets per process run; restart the bot to reset
• Set MAX_SESSION_NOTIONAL=0 to disable the cap entirely

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Wallet Requirements

• USDC.e on Polygon mainnet (collateral for trades)
• POL (formerly MATIC) for gas fees
• Approve USDC.e for Polymarket CTF Exchange and CLOB contracts (bot does this automatically on first EOA run)

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References

• QuickNode Guide — Building a Polymarket Copy Trading Bot
• Polymarket CLOB Client SDK
• Polymarket
• Polymarket CLOB API Docs