Web3 Polymarket

Polymarket Skill

When to use this skill

Use this skill when the user asks about or needs to build:

• Polymarket API authentication (L1/L2, API keys, HMAC signing)
• Placing or managing orders (limit, market, GTC, GTD, FOK, FAK, batch, cancel)
• Reading orderbook data (prices, spreads, midpoints, depth)
• Market data fetching (events, markets, by slug, by tag, pagination)
• WebSocket subscriptions (market channel, user channel, sports)
• CTF operations (split, merge, redeem positions)
• Negative risk markets (multi-outcome, conversion, augmented neg risk)
• Bridge operations (deposits, withdrawals, multi-chain)
• Gasless transactions (relayer client, order attribution)
• Builder program integration (order attribution, API keys, tiers)
• Polymarket SDK usage (TypeScript @polymarket/clob-client, Python py-clob-client)

API Configuration

| API | Base URL | Auth | Purpose |

|-----|----------|------|---------|

| CLOB | https://clob.polymarket.com | L2 for trade endpoints | Orderbook, prices, order submission |

| Gamma / Data | https://gamma-api.polymarket.com | None | Events, markets, search |

| Data API | https://data-api.polymarket.com | None | Trades, positions, user data |

| WebSocket (Market) | wss://ws-subscriptions-clob.polymarket.com/ws/market | None | Real-time orderbook |

| WebSocket (User) | wss://ws-subscriptions-clob.polymarket.com/ws/user | API creds in message | Trade/order updates |

| WebSocket (Sports) | wss://sports-api.polymarket.com/ws | None | Live scores |

| Relayer | https://relayer-v2.polymarket.com/ | Builder headers | Gasless transactions |

| Bridge | https://bridge.polymarket.com | None | Deposits/withdrawals |

Contract Addresses (Polygon)

| Contract | Address |

|----------|---------|

| USDC (USDC.e) | 0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174 |

| CTF (Conditional Tokens) | 0x4D97DCd97eC945f40cF65F87097ACe5EA0476045 |

| CTF Exchange | 0x4bFb41d5B3570DeFd03C39a9A4D8dE6Bd8B8982E |

| Neg Risk CTF Exchange | 0xC5d563A36AE78145C45a50134d48A1215220f80a |

| Neg Risk Adapter | 0xd91E80cF2E7be2e162c6513ceD06f1dD0dA35296 |

Client Setup

TypeScript

import { ClobClient, Side, OrderType } from "@polymarket/clob-client";
import { Wallet } from "ethers"; // v5.8.0

const HOST = "https://clob.polymarket.com";
const CHAIN_ID = 137;
const signer = new Wallet(process.env.PRIVATE_KEY);

// Step 1: L1 — derive API credentials
const tempClient = new ClobClient(HOST, CHAIN_ID, signer);
const apiCreds = await tempClient.createOrDeriveApiKey();

// Step 2: L2 — init trading client
const client = new ClobClient(
  HOST,
  CHAIN_ID,
  signer,
  apiCreds,
  2,                // signatureType: 0=EOA, 1=POLY_PROXY, 2=GNOSIS_SAFE
  "FUNDER_ADDRESS"  // proxy wallet address from polymarket.com/settings
);

Python

from py_clob_client.client import ClobClient
import os

host = "https://clob.polymarket.com"
chain_id = 137
pk = os.getenv("PRIVATE_KEY")

# Step 1: L1 — derive API credentials
temp_client = ClobClient(host, key=pk, chain_id=chain_id)
api_creds = temp_client.create_or_derive_api_creds()

# Step 2: L2 — init trading client
client = ClobClient(
    host,
    key=pk,
    chain_id=chain_id,
    creds=api_creds,
    signature_type=2,  # 0=EOA, 1=POLY_PROXY, 2=GNOSIS_SAFE
    funder="FUNDER_ADDRESS",
)

Quick Reference: Order Types

| Type | Behavior | Use Case |

|------|----------|----------|

| GTC | Rests on book until filled or cancelled | Default limit orders |

| GTD | Active until expiration (UTC seconds). Min = now + 60 + N | Auto-expire before events |

| FOK | Fill entirely immediately or cancel | All-or-nothing market orders |

| FAK | Fill what's available, cancel rest | Partial-fill market orders |

• FOK/FAK BUY: amount = dollar amount to spend
• FOK/FAK SELL: amount = number of shares to sell
• Post-only: GTC/GTD only — rejected if would cross spread

Quick Reference: Signature Types

| Type | Value | Description |

|------|-------|-------------|

| EOA | 0 | Standard Ethereum wallet (MetaMask). Funder is the EOA address and will need POL for gas. |

| POLY_PROXY | 1 | Custom proxy wallet for Magic Link email/Google users who exported PK from Polymarket.com. |

| GNOSIS_SAFE | 2 | Gnosis Safe multisig proxy wallet (most common). Use for any new or returning user. |

Core Pattern: Place an Order

TypeScript

const response = await client.createAndPostOrder(
  {
    tokenID: "TOKEN_ID",
    price: 0.50,
    size: 10,
    side: Side.BUY,
  },
  {
    tickSize: "0.01",  // from client.getTickSize(tokenID) or market object
    negRisk: false,    // from client.getNegRisk(tokenID) or market object
  },
  OrderType.GTC
);
console.log(response.orderID, response.status);

Python

from py_clob_client.clob_types import OrderArgs, OrderType
from py_clob_client.order_builder.constants import BUY

response = client.create_and_post_order(
    OrderArgs(token_id="TOKEN_ID", price=0.50, size=10, side=BUY),
    options={"tick_size": "0.01", "neg_risk": False},
    order_type=OrderType.GTC,
)
print(response["orderID"], response["status"])

Core Pattern: Read Orderbook

TypeScript

// No auth needed
const readClient = new ClobClient("https://clob.polymarket.com", 137);
const book = await readClient.getOrderBook("TOKEN_ID");
console.log("Best bid:", book.bids[0], "Best ask:", book.asks[0]);

const mid = await readClient.getMidpoint("TOKEN_ID");
const spread = await readClient.getSpread("TOKEN_ID");

Python

read_client = ClobClient("https://clob.polymarket.com", chain_id=137)
book = read_client.get_order_book("TOKEN_ID")
mid = read_client.get_midpoint("TOKEN_ID")
spread = read_client.get_spread("TOKEN_ID")

Core Pattern: WebSocket Subscribe

const ws = new WebSocket("wss://ws-subscriptions-clob.polymarket.com/ws/market");

ws.onopen = () => {
  ws.send(JSON.stringify({
    type: "market",
    assets_ids: ["TOKEN_ID"],
    custom_feature_enabled: true,
  }));
  // Send PING every 10s to keep alive
  setInterval(() => ws.send("PING"), 10_000);
};

ws.onmessage = (event) => {
  if (event.data === "PONG") return;
  const msg = JSON.parse(event.data);
  // msg.event_type: "book" | "price_change" | "last_trade_price" | "tick_size_change" | "best_bid_ask" | "new_market" | "market_resolved"
};

Reference files (load on demand)

Only read these when the task requires deeper detail on a specific topic:

• Authentication (L1/L2, builder headers, credential lifecycle): authentication.md
• Order patterns (GTC/GTD/FOK/FAK, tick sizes, cancel, heartbeat, errors): order-patterns.md
• Market data (Gamma API, Data API, CLOB orderbook, subgraph): market-data.md
• WebSocket (market/user/sports channels, subscribe, heartbeat): websocket.md
• CTF operations (split, merge, redeem, neg risk, token IDs): ctf-operations.md
• Bridge (deposits, withdrawals, supported chains/tokens, status): bridge.md
• Gasless transactions (relayer client, wallet deployment, builder setup): gasless.md