We used to have these properties in the WCF Web API configuration.
MaxBufferSize = int.MaxValue,
MaxReceivedMessageSize = int.MaxValue,
If you're self-hosting, it's part of the HttpSelfHostConfiguration class: MSDN Documentation of the HttpSelfHostConfiguration class
It would be used like this:
var config = new HttpSelfHostConfiguration(baseAddress);
config.MaxReceivedMessageSize = int.MaxValue;
config.MaxBufferSize = int.MaxValue;