As far my experience goes using dotnetfiddle.net, the "Tidy Up" functionality only remove unnecessary lines reducing code readability

Add login with Microsoft account

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

Is GC.Collect() implemented? With the 10-MB memory limit. A loop of 75k calls to MD5 ComputeHash runs out of memory. I cannot find a way to recycle memory.

https://dotnetfiddle.net/IjZfxF

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

I have added Automapper v4.2.1 to create some snippets and getting the below error.
Run-time exception (line -1): Could not load type 'AutoMapper.MapperConfiguration' from assembly 'AutoMapper, Version=3.2.1.0, Culture=neutral, PublicKeyToken=be96cd2c38ef1005'.

It looks like that you need to add an assembly redirect field in config to map to take the version added.

Please refer the below fiddle for more
https://dotnetfiddle.net/Widget/fX0mdq

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.

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

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'

Add support for collapsible regions

When try to add nuget package System.Text.Encoding, keep receive error in browser console: common:Uncaught Error:

Uncaught Error: Incorrect version name

at Object.n.addPackage (common:1)

at HTMLAnchorElement.<anonymous> (common:1)

at HTMLBodyElement.dispatch (jquery:1)

at HTMLBodyElement.y.handle (jquery:1)

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

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

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