CircuitBreaker.Net is an implementation of the Circuit Breaker pattern for .NET. This pattern can improve the stability and resiliency of your application, especially in SOAP, microservices and distributed environments. The pattern serves two main purposes: to isolate communication with third-party services, so that your application won't be affected by their fails. And to react to third-party services' fails: it could be a pause, throttling, fail-over, default behavior, etc.
You can read about the pattern on MSDN or from Martin Fowler.

It's available via a nuget package
PM> Install-Package CircuitBreaker.Net

// Initialize the circuit breaker
var circuitBreaker = new CircuitBreaker(
    TaskScheduler.Default,
    maxFailures: 3,
    invocationTimeout: TimeSpan.FromMilliseconds(100),
    circuitResetTimeout: TimeSpan.FromMilliseconds(10000));

try
{
    // perform a potentially fragile call through the circuit breaker
    circuitBreaker.Execute(externalService.Call);
    // or its async version
    // await circuitBreaker.ExecuteAsync(externalService.CallAsync);
}
catch (CircuitBreakerOpenException)
{
    // the service is unavailable, failover here
}
catch (CircuitBreakerTimeoutException)
{
    // handle timeouts
}
catch (Exception)
{
    // handle other unexpected exceptions
}

There are not so many of them. I didn't find any that would suit me. Polly seems the most mature from all of them but it has a locking nature and it doesn't provide a way to specify a separate TaskScheduler to execute actions. But that's a crucial aspect when you call a third-party service, because those calls could stuff your "main" TaskScheduler. Actually none of those libraries support injection of a TaskScheduler. Helpful.CircuitBreaker by RokitSalad isn't thread safe. CircuitBreaker by kylos101 executes actions on the same thread. ManagedCircuitBreaker by AsherW is a fork of Polly with emphasize on IoC containers. The code provided on MSDN isn't production ready and just a piece of code. And so on so forth. So that the yet another library was born. I hope you will find it helpful. 😉