Polymarket

Typed Polymarket prediction-market client for Deno, Bun, Node.js and Cloudflare Workers. It covers Gamma market discovery (no auth), CLOB trading with secp256k1/EIP-712 order signing (L1/L2 auth), portfolio positions and value, and gasless split, merge and redeem. An alternative to the official @polymarket/clob-client for the endpoints it covers.

Overview

One Polymarket client covers both APIs, matching how a Gamma market's clobTokenIds feed directly into CLOB calls:

• Gamma (gamma-api.polymarket.com) — getMarkets() (legacy offset or keyset cursor pagination) and getMarketBySlug(). No credentials needed.
• CLOB (clob.polymarket.com) — getVersion()/getTickSize()/ getNegRisk()/getOrderbook() (public), deriveApiCredentials() (one-time L1-signed onboarding), and L2 HMAC-authenticated getBalance() (USDC collateral, or one outcome token's shares), getOpenOrders()/getFills() (cursor-paginated), submitOrder()/ submitOrders() (single/bulk, up to 15 per request, auto-chunked), cancelOrder()/cancelOrders()/cancelMarketOrders()/ cancelAllOrders().
• Data API (data-api.polymarket.com) — getPositions() and getPortfolioValue(): the public, read-only portfolio view keyed by wallet address (mark-to-market value and PnL). No signing; defaults to auth.funder, reads any wallet via user.
• Relayer (relayer-v2.polymarket.com) — split()/merge()/redeem(), gasless collateral split/merge/redeem via a signed EIP-191 proxy meta-transaction. Requires auth.relayerApiKey/auth.relayerApiKeyAddress, a credential separate from the CLOB's L2 apiCredentials.

submitOrder()/submitOrders()/split()/merge()/redeem() all resolve to the same OrderResult shape (a slippage field included — 0 for SPLIT/MERGE/REDEEM, the requested-vs-actual price gap for a filled BUY/SELL); order() is a single entry point that dispatches to whichever of them a request.action of 'BUY'/'SELL'/'SPLIT'/'MERGE'/'REDEEM' calls for.

Construct with auth.privateKey (and auth.funder for order placement) to use the CLOB; omit auth entirely for Gamma-only, credential-free market data (getOrderbook() and the Data API reads need no credentials either — though the Data API reads default to auth.funder when no user is given).

Key custody

submitOrder() and deriveApiCredentials() sign for real: this client holds your wallet's raw private key in memory for the lifetime of the instance and produces genuine secp256k1 ECDSA signatures over EIP-712 typed data — the same cryptographic operation a browser wallet performs, not a delegated call to one. The key is consumed once at construction, stored in a true (non-enumerable) private field, and never logged, returned, or included in a thrown error. This is the first connect in this repo with a non-@tundralibs dependency — @noble/curves and @noble/hashes (audited, zero-further-dependency, pure JS/TS) — because Web Crypto implements neither secp256k1 ECDSA nor Keccak-256, both of which EIP-712 signing genuinely requires.

A wallet private key is an irreversible-loss-capable secret, unlike a revocable API key. Treat auth.privateKey accordingly: never commit it, prefer a wallet dedicated to this integration over one holding significant funds, and review PolymarketSigner.ts/PolymarketOrder.ts yourself before trusting this client with real money.

split()/merge()/redeem() move real on-chain collateral through a signed EIP-191 meta-transaction relayed by Polymarket's Relayer — review PolymarketRelayer.ts/PolymarketAbi.ts yourself before trusting this client with these calls, the same way you would for order signing.

Out of scope (for now)

• WebSocket market/user feeds (wss://ws-subscriptions-clob.polymarket.com) are real-time push channels, a different integration shape than this repo's REST-only connects; whether/how to add one is an open decision, not yet built.
• Data API activity/leaderboard/holders feeds — only the portfolio half (/positions, /value) is wired up, via getPositions() / getPortfolioValue().

Testing your code

Your tests don't need to fake HTTP. Have your code take a Polymarket instance and pass in a stand-in that returns the shapes from @tundraconnect/polymarket/schemas or throws a real PolymarketError:

import { PolymarketError } from '@tundraconnect/polymarket/errors';

const outage = new PolymarketError('SERVICE_UNAVAILABLE', { status: 503 });
console.log(outage.code);

To exercise the client itself against a fake transport, subclass it and reassign the protected _fetch.

Documentation

Topic	Description
API	Client configuration and endpoint methods
Errors	Error codes and diagnostic metadata
Schemas	Public Guardian schemas and inferred types

Upstream

• Polymarket CLOB API reference
• Polymarket Gamma API reference
• Polymarket trading fees

Installation

Deno:

deno add jsr:@tundraconnect/polymarket

Bun:

bunx jsr add @tundraconnect/polymarket

Node.js:

npx jsr add @tundraconnect/polymarket

Quick Start

import { Polymarket } from '@tundraconnect/polymarket';

// Gamma only — no wallet needed.
const gamma = new Polymarket({});
const { markets } = await gamma.getMarkets({ closed: false, limit: 20 });
const market = markets[0];
console.log(market?.question, market?.clobTokenIds);

// CLOB trading.
const clob = new Polymarket({
  auth: {
    type: 'CUSTOM',
    privateKey: Deno.env.get('CONNECTOR_POLYMARKET_PRIVATE_KEY')!,
    funder: Deno.env.get('CONNECTOR_POLYMARKET_FUNDER')!,
  },
});
await clob.deriveApiCredentials();
const balance = await clob.getBalance();
console.log('USDC available:', balance.balance);

// Portfolio: open orders and fills (CLOB), positions and value (Data API).
const { data: openOrders } = await clob.getOpenOrders();
const positions = await clob.getPositions();
console.log(
  openOrders.length,
  'resting orders,',
  positions.length,
  'positions',
);

const tokenId = market!.clobTokenIds[0]!;
const result = await clob.submitOrder({
  tokenId,
  side: 'BUY',
  price: 0.55,
  shares: 9.0,
  orderType: 'FAK',
});
if (result.filled) {
  console.log(
    `filled: spent ${result.makingAmount} for ${result.takingAmount} shares`,
  );
  console.log('slippage vs. the requested price:', result.slippage);
} else if (result.noMatch) {
  console.log('no resting liquidity matched — nothing was spent');
}

// Kill switch: every resting order, all markets, one request.
await clob.cancelAllOrders();

// order() dispatches BUY/SELL/SPLIT/MERGE/REDEEM to the right call above and
// always returns the same OrderResult shape.
await clob.order({
  action: 'BUY',
  tokenId,
  price: 0.55,
  shares: 9.0,
  orderType: 'FAK',
});

License

MIT. Part of Tundra Connect, typed vendor API clients for Deno, Bun, Node.js and Cloudflare Workers.