Support for System.ServiceModel would be very helpful.

Add Web Api 2.2 to list of project type

Allow the usage of debugging such as stepping into a function, out of a function, run, memory mapping, local variables and the whole nine yards. It is vital if you don't want users to write constantly Console.WriteLine() statements.

Kindly, add debugging!

ScriptCS has a syntax for loading assemblies and works better as a single file. I don't know if you plan on allowing .NET Fiddles (?...is that the plural of the thing you make in .NET Fiddle?) to load other assemblies, but I think it would be really cool to be able to do that.

Currently, dotNetFiddle throws when trying to use Akka.NET.
There is an error message saying that some methods in JSON.NET are missing.
We would love to have the ability to run live Akka samples from our docs site.

This is especially valuable with MVC fiddle type as one cannot add additional views or define their own routing.

So that we can create asynchronous sample in DotNetFiddle

allow us to

1) View the compiled razor
2) allow code folding of codetags and collapse/expand code for readability

We need the same quick keyboard shortcuts as visual studio...
CTRL+D - Duplicate line
CTRL+K+C - Comment out line
CTRL+K+U - Uncomment line
ALT+ENTER - Automatically add or suggest missing namespace reference and add usings to the class (like resharper)

Simple test:

static (int, int) Foo(int i)

{

  return (i+2, 1*2);

}

Current "result" :
Predefined type 'System.ValueTuple`2' is not defined or imported

Expected:
To compile (and work of course :-)

This includes updating "4.7.2" "Compiler" to accept C# 7.x and at least linking the proper dll with ValueTuple-a for "Roslyn 2.0"

There exists five redundant horizontal tabs 0x09 at the second line of all C# templates (Framework, Core, and Roslyn). They have existed for at least a year now.
I am hoping they can be removed.
Thanks.

Support for System.Diagnostics.Debug.Assert could be added. Given that it's an internal verification system that fails when the assertion is incorrect, it could be helpful to at least throw a message in the output window when an assertion wasn't working

Was just trying to run through the c# tutorial and realised the fiddler doesn't allow you to run code with Console.Read etc. Would be a nifty feature :)

It would be nice to see form submits pass through a controller method to another view. Currently I'm just throwing an exception to see passed values (https://dotnetfiddle.net/jZQKsM).

I'm creating some samples for a project, and when using Console.WriteLine inside Tasks, the messages usually won't appear in the log window.

I'm currently required to add a "Thread.Sleep(1000)" or "Task.Delay(1000)" to allow the console buffer to appear.

It would be much better for everyone if this was handled by .NET Fiddle by default.

Allow you to work on whole projects instead of a single at a time. Having the tree listed on the side allowing you to jump from page to page and looking more like a whole project. Also being able to download your project when it's completed

When you add a nuget reference save it in the fiddle so when you open the fiddle again, either on the same machine or a different one, the packages are still there and you don't have to search for them again

When trying to install System.Xml.XPath from NuGet (any version listed in the menu), installation is not allowed and this message is included at the end of the description of the package: "When using NuGet 3.x this package requires at least version 3.4". I think that updating NuGet is an important and urgent step for the functionality of this site. Gracias!

Hi it would be extremely useful if we had the Elvis operator.

On top of each fiddle, it says "by <author's user name>". The author's username should be a link to take the user to all his/her fiddles.