It would come in handy to be able to click either the .NET Fiddle title in the top left corner, or a New Fiddle button to start over. Now, you have to refresh the page or go back to http://dotnetfiddle.net to create a new fiddle.

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.

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"

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

Curley braces autocompletion would be so nice
and shortcut like cw + tab to write Console.WriteLine()

It would be cool to mark some words as `code` and others as *emphasized*.

some class libraries loaded from nuget need setting assembly attributes located in assemplyInfo.cs otherwise it fire an exception, like:

[assembly: AssemblyCompany("Company xyz")]
[assembly: AssemblyCopyright("Copyright © 2018 Company xyz")]

Enable setting these attributes in assemplyInfo.cs

Add support for collapsible regions

With postsharp AOP is available for C#. I wanted to try out a sample code at postharp. I downloaded the nuget package, but it didn't work.

PostSharp extends the C# and VB languages with a notion of pattern. The result: shorter, cleaner code that’s easier to write and understand, contains fewer defects and is less expensive to maintain.

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

why we cant just add our <script src="xyz"> ourselves. Why adding our own css style and javascript in above our html panel doesnt work?

Please create My Fiddles on the left hand side Option's window or on right hand side (New window) so that one can easily switch between files if required.

See this example: https://dotnetfiddle.net/nGSHTF

Typing return at the end of line 7 creates a new line with the wrong indentation. Adding spaces around the equals sign on line 8 causes the line to jump to the wrong indentation level.

This seems to be related to the code on line 7 which splits a string into an array of integers.

TOTAL IDEA :
1 - Font Size Change
2 - Set Automatic Color Syntax According to Commands (Like Notepad++)
3 - Add C++, Python , JavaScript , ... and more
4 - disable problem always set "Autorun on"
5 - Security Type : Public , Links , Private , Passworded
6 - Graph Output like Draw line.....

I get an error when I try to add a reference to System.Data.Entity.Design.PluralizationServices.
'The type of namespace name 'Design' does not exist in the namespace 'System.Data.Entity'