The HttpClient class is more suitable as a singleton for a single app domain. This means the singleton should be shared across multiple container classes. With this tactic, you do get a singleton, but this makes it difficult to share. The HttpClient class implements the IDisposable interface.

Should we create a new single instance of HttpClient for all requests?

Although it implements the IDisposable interface it is actually a shared object. This means that under the covers it is reentrant and thread safe. Instead of creating a new instance of HttpClient for each execution you should share a single instance of HttpClient for the entire lifetime of the application.

Should you reuse HttpClient?

HttpClient is intended to be instantiated once and re-used throughout the life of an application. Instantiating an HttpClient class for every request will exhaust the number of sockets available under heavy loads. This will result in SocketException errors.