Polymarket.Client.Websocket 1.1.1

.NET 6.0 This package targets .NET 6.0. The package is compatible with this framework or higher. .NET Standard 2.0 This package targets .NET Standard 2.0. The package is compatible with this framework or higher. 
dotnet add package Polymarket.Client.Websocket --version 1.1.1
                    


                    

                
NuGet\Install-Package Polymarket.Client.Websocket -Version 1.1.1
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="Polymarket.Client.Websocket" Version="1.1.1" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="Polymarket.Client.Websocket" Version="1.1.1" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="Polymarket.Client.Websocket" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add Polymarket.Client.Websocket --version 1.1.1
                    


                    

                
#r "nuget: Polymarket.Client.Websocket, 1.1.1"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#:package Polymarket.Client.Websocket@1.1.1
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=Polymarket.Client.Websocket&version=1.1.1
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=Polymarket.Client.Websocket&version=1.1.1
                    


                            Install as a Cake Tool

Logo

Polymarket websocket API client

NuGet version Nuget downloads CI build

This is a C# implementation of the Polymarket websocket APIs:

Releases and breaking changes

License

Apache License 2.0

Features

  • installation via NuGet (Polymarket.Client.Websocket)
  • public market API, authenticated user API, sports API, and RTDS
  • targets netstandard2.0, netstandard2.1, net6.0, net7.0, net8.0, net9.0, net10.0
  • built on Websocket.Client 5.5.0 for websocket transport, reconnects, and lower-allocation message handling
  • typed response models: Polymarket stringified prices/sizes are parsed to decimal, timestamps to integer values, and known sides/statuses/topics to enums
  • reactive extensions (Rx.NET)
  • file communicator for replay/backtesting and data collection pipelines, with tests covering collected public market and RTDS websocket frames

Usage

Market channel:

var assetIds = new[] { "217...token-id" };
var url = PolymarketValues.MarketWebsocketApiUrl;

using var communicator = new PolymarketWebsocketCommunicator(url);
using var client = new PolymarketWebsocketClient(communicator);

client.Streams.OrderBookStream.Subscribe(book =>
{
    Console.WriteLine($"Book {book.AssetId}: bids={book.Bids.Length}, asks={book.Asks.Length}");
});

client.Streams.PriceChangeStream.Subscribe(change =>
{
    Console.WriteLine($"Price changes for {change.Market}: {change.PriceChanges.Length}");
});

await communicator.Start();

client.Send(new MarketSubscriptionRequest(assetIds, customFeatureEnabled: true));
client.StartHeartbeat(TimeSpan.FromSeconds(10));

RTDS crypto prices:

var url = PolymarketValues.RtdsWebsocketApiUrl;

using var communicator = new PolymarketWebsocketCommunicator(url);
using var client = new PolymarketWebsocketClient(communicator);

client.Streams.RtdsCryptoPriceStream.Subscribe(price =>
{
    Console.WriteLine($"{price.Symbol}: {price.Value}");
});

await communicator.Start();

client.Send(RtdsSubscriptionRequest.Subscribe(RtdsSubscription.CryptoPrices("btcusdt", "ethusdt")));
client.StartHeartbeat(TimeSpan.FromSeconds(5));

User channel:

var auth = new UserAuth("api-key", "secret", "passphrase");
var url = PolymarketValues.UserWebsocketApiUrl;

using var communicator = new PolymarketWebsocketCommunicator(url);
using var client = new PolymarketWebsocketClient(communicator);

client.Streams.UserOrderStream.Subscribe(order =>
{
    Console.WriteLine($"{order.Status} {order.Side} order {order.Id}");
});

await communicator.Start();

client.Send(new UserSubscriptionRequest(auth));
client.StartHeartbeat(TimeSpan.FromSeconds(10));

More usage examples:

  • integration tests (link)
  • console sample (link)

API coverage

CLOB market channel
Event Covered
book yes
price_change yes
last_trade_price yes
tick_size_change yes
best_bid_ask yes
new_market yes
market_resolved yes
CLOB user channel
Event Covered
order yes
trade yes
Sports channel
Event Covered
sports result update yes
server ping auto-response yes
RTDS
Topic Covered
crypto_prices yes
crypto_prices_chainlink yes
equity_prices live update yes
equity_prices historical snapshot yes
comments yes

Reconnecting

There is a built-in reconnection which invokes after 1 minute (default) of not receiving any messages from the server. It is possible to configure that timeout via communicator.ReconnectTimeout. There is also a stream ReconnectionHappened which sends information about the reconnection type.

You need to resubscribe after reconnection happens. Subscribe to communicator.ReconnectionHappened and send the same subscription request again from that handler.

Polymarket expects client heartbeats:

  • market and user channels: send PING every 10 seconds
  • RTDS: send PING every 5 seconds
  • sports: server sends ping; this client automatically responds with pong by default

Use client.StartHeartbeat(...) for market, user, and RTDS channels.

Backtesting

The library is prepared for backtesting and data collection. The dependency between Client and Communicator is via abstraction IPolymarketCommunicator. There are two communicator implementations:

  • PolymarketWebsocketCommunicator - realtime communication with Polymarket websocket APIs
  • PolymarketFileCommunicator - simulated communication, raw data are loaded from files and streamed

Usage:

var communicator = new PolymarketFileCommunicator
{
    FileNames = new[] { "data/polymarket_raw_sample.txt" },
    Delimiter = ";;"
};

using var client = new PolymarketWebsocketClient(communicator);
client.Streams.PriceChangeStream.Subscribe(change =>
{
    // do something with price changes
});

await communicator.Start();

Multi-threading

Observables from Reactive Extensions are single threaded by default. Your code inside subscriptions is called synchronously as soon as a message comes from the websocket API. If your subscription handler takes a long time, it blocks the receiving method, buffers messages, and can eventually lose messages.

Handle messages on another thread when your processing is expensive:

client
    .Streams
    .PriceChangeStream
    .ObserveOn(TaskPoolScheduler.Default)
    .Subscribe(change => { /* process */ });

If you need parallel processing while preserving order for a stream, use synchronization:

private static readonly object Gate = new object();

client
    .Streams
    .PriceChangeStream
    .ObserveOn(TaskPoolScheduler.Default)
    .Synchronize(Gate)
    .Subscribe(change => { /* process */ });

Pull Requests are welcome!

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 is compatible.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 is compatible.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 is compatible.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 is compatible. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
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Version Downloads Last Updated
1.1.1 104 5/19/2026
1.1.0 84 5/19/2026
1.0.0 89 5/19/2026

Add collected public websocket replay coverage for market and RTDS streams, and use a NuGet.org-compatible README logo URL.