Polymarket.Net 2.2.0

Polymarket.Net

Polymarket.Net is a client library for accessing the Polymarket REST and Websocket API.

Features

• Response data is mapped to descriptive models
• Input parameters and response values are mapped to discriptive enum values where possible
• High performance
• Automatic websocket (re)connection management
• Client side rate limiting
• Client side order book implementation
• Support for managing different accounts
• Extensive logging
• Support for different environments
• Easy integration with other exchange clients based on the CryptoExchange.Net base library
• Native AOT support

Supported Frameworks

The library is targeting both .NET Standard 2.0 and .NET Standard 2.1 for optimal compatibility, as well as the latest dotnet versions to use the latest framework features.

Install the library

NuGet

dotnet add package Polymarket.Net

GitHub packages

Polymarket.Net is available on GitHub packages. You'll need to add https://nuget.pkg.github.com/JKorf/index.json as a NuGet package source.

Download release

The NuGet package files are added along side the source with the latest GitHub release which can found here.

How to use

Basic request:

// Get the order book info for the outcomes of the first market via rest request
var markets = await polymarketRestClient.GammaApi.GetMarketsAsync(closed: false);
if (!markets.Success)
{
	Console.WriteLine("Failed: " + markets.Error);
	return;
}

var firstMarket = markets.Data[0];
var bookInfo = await polymarketRestClient.ClobApi.ExchangeData.GetOrderBooksAsync(firstMarket.ClobTokenIds!);

Place order:

var restClient = new PolymarketRestClient(opts => {
	opts.ApiCredentials = new PolymarketCredentials(new PolymarketL1Credential("PRIVATEKEY", "PRIVATESIGNERKEY"));
});

// Update the client with layer 2 credentials
var credentials = await polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync();
polymarketRestClient.UpdateL2Credentials(credentials.Data);

// Place Limit order to buy 50 shared at 0.1 ($10)
var tokenIdTest = "67565972075898091709163371829761231762318232475740950317083391526954889294846";
var result = await polymarketRestClient.ClobApi.Trading.PlaceOrderAsync(
    tokenIdTest, 
	OrderSide.Buy,
	OrderType.Limit, 
	50, 
	price: 0.1m,
	feeRateBps: 0);

WebSocket subscription:

// Subscribe to updates for a specific token/asset via the websocket API
var socketClient = new PolymarketSocketClient();
var tokenId = "11862165566757345985240476164489718219056735011698825377388402888080786399275";
var subscriptionResult = await polymarketSocketClient.ClobApi.SubscribeToTokenUpdatesAsync([tokenId2],
	priceUpdate =>
	{
		// Handle price change update
	},
	bookUpdate =>
	{
		// Handle order book update
	},
	lastTradePriceUpdate =>
	{
		// Handle last trade price update
	},
	tickSizeUpdate =>
	{
		// Handle tick size update
	},
	bestBidAskUpdate =>
	{
		// Handle best bid/ask change update
	});

Authentication

Authenticate using an email account and providing the exported private key and the funding address. This will require you to request the layer 2 credentials before orders can be placed:

var credsEmailLayer1 = new PolymarketCredentials(
	new PolymarketL1Credential(
		SignType.Email, // Email wallet, when creating a new wallet via the web interface
		"0x00..", // The private key, can be exported from the web interface
		"0x00..")); // The polymarket funding address, can be found in the web interface under `Profile -> Your Polymarket Wallet Address`

Authenticate using an email account and providing the exported private key and the funding address, while also providing previously requested layer 2 credentials. Can be used to place orders directly:

var credsEmailWithLayer2 = new PolymarketCredentials(
    new PolymarketL1Credential(
        SignType.Email,// Email wallet, when creating a new wallet via the web interface
        "0x00..",// The private key, can be exported from the web interface
        "0x00.."), // The polymarket funding address, can be found in the web interface under `Profile -> Your Polymarket Wallet Address`
    new HMACPassCredential(
        "KEY",// The L2 API key as previously retrieved with `polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync()`
        "SEC", // The L2 API secret as previously retrieved with `polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync()`
        "PASS" // The L2 API passphrase as previously retrieved with `polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync()`
    ));

Authenticate using an external account, for example MetaMask, and providing the private key. This will require you to request the layer 2 credentials before orders can be placed:

var credsEoaLayer1 = new PolymarketCredentials(
    new PolymarketL1Credential(
        SignType.EOA, // Externally Owned Account wallet, when using an existing wallet to connect to polymarket
        "0x00..")); // The private key for the wallet

Authenticate using an external account, for example MetaMask, and providing the private key, while also providing previously requested layer 2 credentials. Can be used to place orders directly:

var credsEoaWithLayer2 = new PolymarketCredentials(
    new PolymarketL1Credential(
        SignType.EOA, // Externally Owned Account wallet, when using an existing wallet to connect to polymarket
        "0x00.." // The private key for the wallet
    ),
    new HMACPassCredential(
        "KEY", // The L2 API key as previously retrieved with `polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync()`
        "SEC", // The L2 API secret as previously retrieved with `polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync()`
        "PASS" // The L2 API passphrase as previously retrieved with `polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync()`
    ));

Retrieve and set layer 2 credentials need for placing orders (required when L2 credentials not provided in the credentials):

var credentialResult = await polymarketRestClient.ClobApi.Account.GetOrCreateApiCredentialsAsync();
if (credentialResult.Success)
    polymarketRestClient.UpdateL2Credentials(credentialResult.Data);

Set the previously created credentials:

// Via constructor
var client = new PolymarketRestClient(options =>
{
    options.ApiCredentials = credentials;
});

// Via dependency injection
services.AddPolymarket(options =>
{
    options.ApiCredentials = credentials
});

For information on the clients, dependency injection, response processing and more see the documentation, or have a look at the examples here or here.

CryptoExchange.Net

Polymarket.Net is based on the CryptoExchange.Net base library. Other exchange API implementations based on the CryptoExchange.Net base library are available and follow the same logic.

CryptoExchange.Net also allows for easy access to different exchange API's.

Exchange	Repository	Nuget
Aster	JKorf/Aster.Net
Binance	JKorf/Binance.Net
BingX	JKorf/BingX.Net
Bitfinex	JKorf/Bitfinex.Net
Bitget	JKorf/Bitget.Net
BitMart	JKorf/BitMart.Net
BitMEX	JKorf/BitMEX.Net
Bitstamp	JKorf/Bitstamp.Net
BloFin	JKorf/BloFin.Net
Bybit	JKorf/Bybit.Net
Coinbase	JKorf/Coinbase.Net
CoinEx	JKorf/CoinEx.Net
CoinGecko	JKorf/CoinGecko.Net
CoinW	JKorf/CoinW.Net
Crypto.com	JKorf/CryptoCom.Net
DeepCoin	JKorf/DeepCoin.Net
Gate.io	JKorf/GateIo.Net
HTX	JKorf/HTX.Net
HyperLiquid	JKorf/HyperLiquid.Net
Kraken	JKorf/Kraken.Net
Kucoin	JKorf/Kucoin.Net
Mexc	JKorf/Mexc.Net
OKX	JKorf/OKX.Net
Toobit	JKorf/Toobit.Net
Upbit	JKorf/Upbit.Net
Weex	JKorf/Weex.Net
WhiteBit	JKorf/WhiteBit.Net
XT	JKorf/XT.Net

When using multiple of these API's the CryptoClients.Net package can be used which combines this and the other packages and allows easy access to all exchange API's.

Discord

A Discord server is available here. For discussion and/or questions around the CryptoExchange.Net and implementation libraries, feel free to join.

Supported functionality

REST Central Limit Order Book (CLOB) API

REST Gamma API

Websocket API

Support the project

Any support is greatly appreciated.

Donate

Make a one time donation in a crypto currency of your choice. If you prefer to donate a currency not listed here please contact me.

Btc: bc1q277a5n54s2l2mzlu778ef7lpkwhjhyvghuv8qf
Eth: 0xcb1b63aCF9fef2755eBf4a0506250074496Ad5b7
USDT (TRX) TKigKeJPXZYyMVDgMyXxMf17MWYia92Rjd

Sponsor

Alternatively, sponsor me on Github using Github Sponsors.

Release notes

• Version 2.2.0 - 24 Apr 2026

  • Added QuantityType parameter to PlaceOrder endpoints which allows to specify market buy orders in USD value instead of number of shares
  • Updated book caching logic to only store for 2 seconds instead of indefinitely to fix outdated info preventing correct order placement
  • Fixed PolymarketTrade Role mapping

• Version 2.1.1 - 13 Apr 2026

  • Default timeInForce to ImmediateOrCancel for market orders if parameter not provided
  • Fixed order quantity rounding issues

• Version 2.1.0 - 09 Apr 2026

  • Updated CryptoExchange.Net to version 11.1.0, see https://github.com/JKorf/CryptoExchange.Net/releases/ for full release notes
  • Added Polymarket Data API support
  • Improved socketClient.ClobApi.SubscribeToTokenUpdatesAsync registration logic
  • Fixed parameters not getting send with various requests
  • Fixed startTimeMin, startTimeMax parameter serialization on GammaApi GetMarketsAsync and GetEventsAsync

• Version 2.0.0 - 24 Mar 2026

  • Updated CryptoExchange.Net to version 11.0.1, see https://github.com/JKorf/CryptoExchange.Net/releases/ for full release notes

  • Updated class for supplying API credentials from ApiCredentials to PolymarketCredentials

  • Updated Shared order status parsing to default to Unknown value if not parsable

  • Updated signing logic to unified logic in the CryptoExchange.Net library

  • Added cursor parameter to restClient.ClobApi.Trading.GetOpenOrdersAsync endpoint

  • Updated PolymarketEvent ParentEvent to ParentEventId and changed type to long?

  • Fixed SubscribeToPlatformUpdatesAsync onMarketResolved handling

  • Fixed exception in PolymarketSocketClient.UpdateL2Credentials

  • Fixed parameter serialization restClient.ClobApi.Account.GetBuilderTradesAsync endpoint

  • Fixed parameter serialization restClient.ClobApi.Trading.GetOpenOrdersAsync endpoint

  • Notes for updating:

    • Update ApiCredentials to PolymarketCredentials for authentication, and provided L1 and L2 credentials separately, i.e. ApiCredentials = new ApiCredentials(signType, l1key, l1fundkey, l2key, l2sec, l2pass) ⇒ ApiCredentials = new PolymarketCredentials(new PolymarketL1Credential(signType, l1key, l1fundkey), new HMACPassCredential(l2key, l2sec, l2pass))

• Version 1.5.2 - 10 Mar 2026

  • Updated order quantity/price rounding
  • Updated xml comments to include json fields

• Version 1.5.1 - 06 Mar 2026

  • Fixed bug in market order buy price determination
  • Fixed exception in PlaceOrderAsync when placing a market order when order book is empty
  • Fixed incorrect parameter serialization in restClient.ClobApi.Trading.GetUserTradesAsync endpoint
  • Fixed order expiration serialization in PlaceOrder endpoints
  • Fixed conditionIds not getting sent in restClient.GammaApi.GetMarketsAsync endpoint

• Version 1.5.0 - 06 Mar 2026

  • Updated CryptoExchange.Net to version 10.8.0, see https://github.com/JKorf/CryptoExchange.Net/releases/ for full release notes
  • Improved method XML comments

• Version 1.4.1 - 26 Feb 2026

  • Updated LastTradePrice on PolymarketBookUpdate model to nullable

• Version 1.4.0 - 24 Feb 2026

  • Updated CryptoExchange.Net to version 10.7.0
  • Added restClient.ClobApi.Trading.PostOrderHeartbeatAsync endpoint
  • Added websocket ping message sending
  • Added additional Http settings to client options
  • Updated Shared REST interfaces pagination logic
  • Updated HttpClient registration, fixing issue of DNS changes not getting processed
  • Fixed UserClientProvider using unconfigured HttpClient

• Version 1.3.1 - 17 Feb 2026

  • Updated CryptoExchange.Net to version 10.6.2, see https://github.com/JKorf/CryptoExchange.Net/releases/ for full release notes
  • Fixed not correctly handling book snapshot websocket update

• Version 1.3.0 - 16 Feb 2026

  • Updated CryptoExchange.Net to version 10.6.0, see https://github.com/JKorf/CryptoExchange.Net/releases/ for full release notes
  • Fixed SymbolOrderBook websocket subscription not getting closed if when waiting for initial data times out

• Version 1.2.0 - 10 Feb 2026

  • Updated CryptoExchange.Net to version 10.5.1, see https://github.com/JKorf/CryptoExchange.Net/releases/ for full release notes
  • Updated UserClientProvider internal client cache to non-static to prevent cleanup issues
  • Fixed websocket token subscription price change topic mapping

• Version 1.1.0 - 06 Feb 2026

  • Updated CryptoExchange.Net to version 10.4.0, see https://github.com/JKorf/CryptoExchange.Net/releases/ for full release notes
  • Added OrderStatus.Matched value
  • Fixed disposed clients getting returned from UserClientProvider

• Version 1.0.1 - 27 Jan 2026

  • Fixed signing issue certain token values
  • Fixed rounding issue in quantity calculation

• Version 1.0.0 - 22 Jan 2026

  • Initial release