I would like to be able to create projects that contain multiple files so that I can create tutorials to teach student.
The MVC project type for example allows for multiple files. but they are all together on screen and I can't close one down to focus on say the controller.

VS Code uses Theia https://www.theia-ide.org/index.html - Perhaps you could also use this in your UI?

This would really help to make samples of bugs / issues in a repository. One could import all the files of a repository, then write a "Test" that fails and the owner of the repository could then check out why it fails easily.

See for example me manually uploading the files in a competitors product:
https://repl.it/@devedse/ErrorWhenLoadingJpgWithExif

Sometimes I need to check a code that works with local timezone which should be different from UTC. It would be great to have an ability to specify timezone in that cases. Thank you!

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"

Why would you make a Nuget Header Directive available for C# but not for VB.Net?

It would be nice to have a user page that lists the Fiddles that we have created. A main page of sorts.

Such as controller or class or new .cHTML ...

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!

Monaco-editor is MIT licensed and made by Microsft.
It's the same text editor used in VSCode, and it is open source!
It also has many interesting features like code diff and editor customization.

See more here:
https://github.com/Microsoft/monaco-editor
https://microsoft.github.io/monaco-editor/playground.html

Please give us inverted color theme, most developers are working with "white on black"

Support for System.ServiceModel would be very helpful.

Roslyn 2.0 is currently in pre-release state. As we get close to RTM, dotnetFiddle will be quite useful to try or demo C# 7 features.

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)

Given that MS have stopped supporting 4.5.1 and dotnet core has been released, it would be a good time to update the examples.

I would love to use .NET Fiddle in the documentation pages for my OSS projects, but I can't install the packages (I think because of the Framework verisons)

Please create mobile app for this wonderful service. It may help lots of people where accessing laptops or systems is not easy.

Full roslyn release support