12 Best Online C# Compilers in 2026: Features and Comparison

Want to write and run C# code without installing Visual Studio or setting up the .NET SDK? An online C# compiler allows you to write, compile and execute programs directly from your web browser.

Whether you're learning C#, solving programming problems, preparing for technical interviews or experimenting with .NET features, online compilers can save considerable setup time.

However, not all online C# compilers provide the same functionality. Some are designed for beginners, while others support multiple .NET runtimes, external packages, debugging or cloud based project development.

In this article, we'll explore 12 online C# compilers available in 2026. We'll compare their features, explain their limitations and help you choose a suitable platform for your programming requirements.

What is an online C# compiler?

An online C# compiler is a web based development tool that allows programmers to write, compile and execute C# programs without installing development software on their computers.

Most online compilers include a source code editor, a compilation environment and a console for displaying program output. Some also provide debugging capabilities, package integration and code sharing functionality.

When you execute a C# program, its source code is typically compiled into Common Intermediate Language (CIL). The .NET runtime then executes the compiled code, often using just-in-time compilation to generate native machine instructions.

Online compilers handle much of this process on remote servers, allowing users to concentrate on writing and testing code.

Quick comparison of the 12 online C# compilers

The following table provides a quick overview of the platforms discussed in this article.

The table describes the platforms' advertised capabilities. Runtime versions, account requirements and language specific debugger availability may change.

12 best online C# compilers

1.NET Fiddle

Website: dotnetfiddle.net

.NET Fiddle is an online programming environment built specifically for .NET technologies. It allows developers to write, compile, execute and share C# programs through a web browser.

Unlike general-purpose online compilers, .NET Fiddle focuses on the .NET ecosystem. It supports languages including C#, VB.NET and F#.

One useful feature is its NuGet package integration. Instead of creating a separate local project, programmers can experiment with compatible packages inside the browser.

.NET Fiddle also supports features such as code formatting, automatic execution, saving, forking and inspecting Intermediate Language.

Key features

• Supports C#, VB.NET and F#.
• Integrates compatible NuGet packages.
• Provides automatic execution and source code formatting.
• Allows developers to save, share and fork code.
• Supports viewing generated Intermediate Language.
• Includes additional functionality such as database templates.

Advantages

.NET Fiddle provides a convenient environment for testing .NET specific functionality. Its NuGet integration is useful when experimenting with third-party libraries.

The ability to inspect generated IL also makes it interesting for developers who want to understand how C# code is compiled.

Limitations

Although .NET Fiddle provides several advanced features, it is not a complete replacement for a desktop development environment.

Developers maintaining large applications with multiple services, complicated build configurations or advanced debugging requirements may need a local IDE.

When should you use .NET Fiddle?

Use .NET Fiddle when testing .NET functionality, experimenting with compatible NuGet packages, reproducing programming problems or sharing code examples with other developers.

2. SharpLab

Website: sharplab.io

SharpLab is a specialized .NET programming playground designed to help developers understand what happens when C# code is compiled.

While conventional online compilers primarily focus on executing source code, SharpLab allows users to inspect several stages of the compilation process.

For example, you can write a C# program and examine its Intermediate Language, decompiled C# or JIT-generated assembly. This functionality is especially useful for understanding language features, compiler transformations and runtime behavior.

SharpLab supports C#, Visual Basic and F#. It also provides a Run target for executing supported programs, although execution has intentional restrictions.

Key features

• Supports C#, Visual Basic and F#.
• Displays compiled Intermediate Language.
• Provides decompiled C# output.
• Allows developers to inspect JIT assembly.
• Includes a code execution option with restrictions.
• Helps visualize how the compiler transforms language constructs.

Advantages

SharpLab provides insights that ordinary online compilers generally do not expose.

For example, programmers can compare different C# implementations and inspect the generated code to better understand compiler behavior.

This is particularly useful when studying advanced language features or investigating performance related questions.

However, inspecting generated assembly is not a substitute for measuring actual application performance.

Limitations

SharpLab is a specialized programming playground rather than a general purpose cloud IDE.

Its execution environment is intentionally restricted, and developers should not expect it to provide the full functionality of a traditional .NET development environment.

When should you use SharpLab?

Use SharpLab when learning advanced C#, exploring compiler transformations, examining generated IL or investigating how particular C# constructs are implemented.

3. JDoodle

Website: jdoodle.com/compile-c-sharp-online

JDoodle is an online compiler and development environment that supports C# alongside numerous other programming languages.

One of its distinguishing features is its support for multiple C# execution environments.

According to its current documentation, JDoodle provides several Mono versions as well as .NET 7 and .NET 10. Developers can select an available runtime before executing their programs.

JDoodle also supports compatible public NuGet packages and provides a separate multi file development environment.

Key features

• Supports multiple C# execution environments.
• Offers Mono, .NET 7 and .NET 10 options.
• Supports compatible public NuGet packages.
• Provides syntax highlighting and code completion.
• Includes automatic bracket matching and code folding.
• Offers a separate multi file C# IDE.

Advantages

JDoodle is useful when developers need to experiment with code across different supported runtimes.

Its NuGet integration allows users to test certain third-party libraries without configuring a local development environment.

Another advantage is its separate multi-file IDE, which provides more flexibility than a traditional single file online compiler.

Limitations

The standard online compiler is intended for single-file programs. Developers working with multiple source files must use JDoodle's separate IDE.

Private or locally stored NuGet packages are not supported through the standard compiler.

Although users can execute programs without registering, saving projects and accessing certain additional features requires an account.

When should you use JDoodle?

JDoodle is useful when testing runtime compatibility, experimenting with public NuGet packages or writing C# programs that require more than a basic compiler.

4. OneCompiler

Website: onecompiler.com/csharp

OneCompiler is a browser-based compiler that allows users to write, execute and share C# programs online.

Its straightforward interface makes it suitable for beginners and experienced programmers who want to test small programs without configuring a local environment.

When you open its C# compiler, it provides sample boilerplate code that you can modify.

OneCompiler also supports standard input, allowing users to test programs that require keyboard input.

Key features

• Browser-based C# code editor.
• Ready to use example programs.
• Standard input support.
• Code execution and output display.
• Code sharing functionality.
• Support for additional programming languages.

Advantages

One Compiler makes it easy to experiment with C# syntax and fundamental programming concepts.

Students can practice conditional statements, loops, arrays and methods without spending time installing development software.

Its standard input functionality also makes it useful for solving programming problems that require user input.

Limitations

OneCompiler's basic compiler interface is primarily designed for executing code.

Developers requiring advanced debugging, complex project configurations or specialized .NET packages may need a more comprehensive environment.

When should you use OneCompiler?

Choose OneCompiler for everyday C# practice, testing short programs, learning programming concepts or preparing for technical interviews.

5. OnlineGDB

Website: onlinegdb.com/online_csharp_compiler

OnlineGDB combines an online code editor with compilation and debugging related functionality.

Its C# environment provides an editor, execution controls, input options and output panels. It also includes editor customization features.

Developers can modify settings such as themes, font size, autocomplete and word wrapping. The platform also provides options for saving, sharing and downloading code.

Although its interface advertises debugging functionality, developers should verify the availability of individual debugger features for C#.

Key features

• Browser based C# code editor.
• Compilation and execution.
• Standard input and command line argument options.
• Syntax highlighting and autocomplete settings.
• Editor customization.
• Debugging interface.
• Project sharing and downloading.

Advantages

OnlineGDB brings several useful programming controls into a single browser based interface.

Its input and output options are particularly helpful when practicing programming exercises.

The customization settings also allow users to adapt the editing environment to their preferences.

Limitations

Debugger functionality can differ between programming languages, so its C# debugging capabilities should be evaluated against your requirements.

It is also not intended to replace a complete desktop development environment for substantial .NET applications.

When should you use OnlineGDB?

OnlineGDB is useful for practicing C#, executing programs that require input and experimenting with code in a customizable browser-based editor.

Read our guide on what debugging is to understand how debugging helps developers identify programming errors.

6. Replit

Website: replit.com/languages/csharp

Replit is a cloud based software development platform that supports C# and several other programming languages.

Unlike traditional online compilers that focus on executing individual code snippets, Replit provides a broader development environment for creating, maintaining and sharing projects.

Developers can use Replit to experiment with C# without first configuring a conventional desktop IDE. The platform also provides AI assisted development features.

Its current C# page requires users to sign up to start coding, so developers seeking an immediate, registration free compiler may prefer another option.

Key features

• Cloud hosted development environment.
• Browser based C# programming.
• Persistent project workspaces.
• Project sharing functionality.
• AI assisted development.
• Support for multiple programming languages.

Advantages

Replit is particularly useful when developers need a cloud based environment for more than an occasional programming exercise.

Its project oriented approach allows users to maintain their work instead of repeatedly creating standalone code snippets.

The platform's broader development capabilities can also be useful for experimenting with application ideas.

Limitations

Replit requires registration for its C# environment, and access to particular features depends on the available subscription.

Developers should verify the runtime version, available resources and project compatibility before using it for an existing application.

Its additional functionality may be unnecessary for programmers who simply want to execute a few lines of C#.

When should you use Replit?

Consider Replit when developing cloud hosted coding projects, working across different devices or exploring AI assisted development.

7. Programiz

Website: programiz.com/csharp-programming/online-compiler

Programiz provides a free online C# compiler designed to make programming accessible to beginners.

Its main advantage is the combination of a simple browser based compiler and educational resources.

Students can read a tutorial, practice the concepts in its compiler and examine the resulting output without installing the .NET SDK or configuring an IDE.

Programiz also recommends installing C# locally when users progress to more complex applications involving multiple files and folders.

Key features

• Free browser based C# compiler.
• No local installation required.
• Simple coding environment.
• Accompanying C# tutorials.
• Programming examples covering fundamental concepts.
• Separate online compilers for other programming languages.

Advantages

Programiz makes it convenient to learn C# without dealing with the configuration requirements of professional development environments.

Its educational resources help beginners understand basic programming concepts before attempting larger projects.

Students can use the compiler to experiment with examples involving variables, operators, conditional statements, loops and methods.

Limitations

Programiz is primarily focused on learning and running relatively simple programs.

Developers requiring advanced debugging, elaborate build configurations, external package management or complex project structures may prefer another environment.

When should you use Programiz?

Programiz is suitable for beginners learning C#, students completing introductory programming exercises and anyone who wants a straightforward environment for practicing syntax.

If you're new to the language, read our introduction to C# programming .

8. W3Schools

Website: w3schools.com/CS/cs_compiler.php

W3Schools offers an online C# compiler that allows users to edit programs and view their output directly in a browser.

Its compiler complements the platform's C# tutorials, which cover topics ranging from basic syntax to object oriented programming.

The learning process is straightforward. You can read a tutorial, experiment with the accompanying example and execute the modified code to see how it behaves.

W3Schools also promotes its separate Spaces service for creating and managing larger online projects.

Key features

• Browser based C# compiler.
• Interactive code editing and execution.
• Ready to use examples.
• Integration with C# tutorials.
• Additional exercises and quizzes.
• Separate project building functionality through W3Schools Spaces.

Advantages

W3Schools provides a convenient combination of programming explanations and practical exercises.

Rather than switching between a tutorial and a separate development environment, beginners can modify examples and immediately examine the results.

This approach is useful when learning unfamiliar programming concepts.

Limitations

The standard W3Schools compiler is designed primarily for educational exercises.

Its basic interface does not provide the extensive debugging, project management and package integration capabilities associated with professional .NET development environments.

When should you use W3Schools?

Use W3Schools when learning C# through tutorials, experimenting with introductory code examples or revising programming fundamentals.

9. TutorialsPoint

Website: tutorialspoint.com/compilers/online-csharp-compiler.htm

TutorialsPoint offers an online C# compiler alongside its programming tutorials and educational resources.

Its C# compiler provides predefined examples covering fundamental concepts such as variables, conditions, arrays, functions, classes, recursion and exception handling.

Users can select an example, modify its code, execute it and review the output.

The current compiler page identifies its environment as Mono and displays execution controls, input options and debugging-related interface elements. However, not every displayed debugging feature is necessarily available for C#.

Key features

• Browser based C# code editor.
• Ready made programming examples.
• Program input and output.
• Source code copying and downloading.
• Educational tutorials.
• Debugging related interface elements.
• AI coding assistance.

Advantages

TutorialsPoint is useful for learners who prefer working through practical examples.

Its collection of sample programs makes it convenient to explore different C# concepts without writing every program from scratch.

Students can change the examples to observe how individual statements affect program behavior.

Limitations

TutorialsPoint's advertised C# compiler uses Mono, so developers should verify compatibility with the language features their code requires.

Its educational environment should not be treated as a complete replacement for a professional .NET IDE.

When should you use TutorialsPoint?

TutorialsPoint is suitable for practicing fundamental C# concepts, experimenting with sample programs and learning through interactive examples.

10. CodeChef

Website: codechef.com/ide

CodeChef provides an online programming environment alongside its coding competitions, tutorials and programming practice resources.

Its online IDE supports numerous programming languages. CodeChef's published compiler list includes C# through Mono's gmcs 6.12 compiler.

The platform is particularly relevant for programmers who want to practice solving computational problems and prepare for coding competitions.

When working with competitive programming problems, developers often need to read input, process it and generate output in a specific format.

An online IDE makes it convenient to experiment with solutions without repeatedly configuring a local programming environment.

Key features

• Multi-language online programming environment.
• C# included in its published compiler list.
• Access to competitive programming resources.
• Programming exercises and educational content.
• Browser-based coding environment.

Advantages

CodeChef provides an environment connected to programming challenges and competitive coding practice.

Developers can use its educational resources to explore algorithms and data structures while practicing their preferred programming language.

Its published compiler list also allows C# users to identify the advertised compilation environment.

Limitations

CodeChef is primarily associated with competitive programming rather than professional .NET application development.

Developers working with newer C# language features should carefully consider its published Mono compiler version.

Its online IDE should not be confused with a full featured development environment for building substantial .NET applications.

When should you use CodeChef?

CodeChef is worth considering when practicing algorithms, solving competitive programming problems or preparing for programming assessments.

11. Ideone

Website: ideone.com

Ideone is an online compiler and execution environment supporting more than 60 programming languages.

It allows users to enter source code, provide optional input and execute programs remotely.

The platform uses Sphere Engine technology to provide its remote code execution environment.

Its multi language support makes Ideone useful for programmers who regularly work with different languages or want to compare implementations of the same programming problem.

Key features

• Supports more than 60 programming languages.
• Browser based code editing.
• Optional standard input.
• Syntax highlighting.
• Program execution and output.
• Code sharing functionality.
• Remote execution through Sphere Engine.

Advantages

Ideone provides a straightforward way to run short programs without configuring separate development environments.

Its language support is useful for programmers who want to explore different implementations of the same algorithm.

Developers can also use it to share small programming examples with other users.

Limitations

Ideone primarily focuses on code execution rather than offering an extensive project oriented development environment.

Although the platform describes itself as a compilation and debugging tool, developers should not assume that it provides the same interactive debugging capabilities as a desktop IDE.

Programs requiring complex dependencies or elaborate project configurations may be better suited to other environments.

When should you use Ideone?

Ideone is useful for running short C# programs, experimenting with different programming languages and sharing code examples.

12. GeeksforGeeks

Website: geeksforgeeks.org/ide/online-csharp-compiler

GeeksforGeeks provides an online programming environment alongside its tutorials, coding exercises and interview preparation resources.

Its online IDE includes C# among the programming languages available for selection.

Developers can use its code editor to practice programming problems, experiment with algorithms and execute code through a browser.

Key features

• Multi language online code editor.
• C# language support.
• Code execution environment.
• Input and output functionality.
• Access to programming tutorials.
• Coding and interview preparation resources.

Advantages

GeeksforGeeks combines programming resources with an online coding environment.

Students can study a programming concept, attempt a related problem and experiment with code without leaving the broader learning platform.

This makes it useful for programmers preparing for technical interviews or revising fundamental concepts.

Limitations

The online IDE is primarily intended for programming practice rather than advanced .NET application development.

Developers requiring specific runtime versions, extensive debugging or specialized libraries should confirm that the platform supports their requirements.

When should you use GeeksforGeeks?

Consider GeeksforGeeks when practicing programming problems, revising C# concepts or preparing for technical interviews.

Which online C# compiler should you choose?

Different compilers are suitable for different programming tasks. Rather than choosing a platform based solely on its popularity, consider what you want to accomplish.

LEARNING C# FROM SCRATCH

Programiz, W3Schools, TutorialsPoint

Simple editors alongside educational resources.

TESTING .NET LIBRARIES

.NET Fiddle, JDoodle

Documented support for compatible NuGet packages.

UNDERSTANDING COMPILER BEHAVIOR

SharpLab, .NET Fiddle

Generated Intermediate Language and additional compilation insights.

TESTING MULTIPLE RUNTIMES

JDoodle

Provides a documented selection of Mono and .NET environments.

PRACTICING CODING PROBLEMS

OneCompiler, CodeChef, GeeksforGeeks

Suitable environments for running exercises and exploring algorithms.

DEVELOPING CLOUD-HOSTED PROJECTS

Replit, JDoodle's multi-file IDE

Project-oriented environments rather than exclusively single-file execution.

RUNNING SHORT PROGRAMS

OneCompiler, Ideone, OnlineGDB

Browser-based editors with straightforward execution workflows.

These suggestions reflect documented features and intended use cases, not comparative speed or usability testing.

How to run C# code using an online compiler

Most online C# compilers follow a similar execution process. Here's a simple example that you can try using one of the platforms discussed above.

1. Open your preferred online compiler.
   For example, visit OneCompiler or JDoodle .

Enter your C# program.
Paste the following example into the code editor.

using System;

class Program

{

static void Main()

{

Console.Write("Enter your name: ");

string name = Console.ReadLine() ?? "Guest";

Console.WriteLine($"Hello, {name}!");

}

}

1. Provide input.
   If the platform has a separate standard-input field, enter Alex. Otherwise, enter the name when the program prompts you.
2. Execute the program.
   Click the Run or Execute button. The platform will attempt to compile and execute your code.

Review the result.
The expected program output is:

Enter your name: Hello, Alex!

1. 
   Some compilers display the entered input separately or include execution information.

Try modifying the program to display a different message. You can also introduce a syntax error intentionally to understand how the compiler reports programming mistakes.

How to choose an online C# compiler

Several factors can influence your choice of compiler.

1. C# language and .NET runtime compatibility

Not every online compiler supports the same C# language version or .NET runtime.

This becomes important when experimenting with modern language features or maintaining applications developed for older runtime environments.

For example, JDoodle documents support for several Mono versions, .NET 7 and .NET 10. TutorialsPoint currently advertises a Mono-based C# environment, while CodeChef lists a specific Mono compiler in its documentation.

Always verify the supported language and runtime versions before selecting a platform.

2. Debugging capabilities

A compiler identifies compilation errors, while a debugger helps developers investigate program behavior during execution.

If debugging is important, look for capabilities such as breakpoints, step by step execution, variable inspection and call-stack information.

Some multi language platforms display debugging controls without offering identical functionality for every language.

Confirm that the relevant debugger features work specifically with C#.

For further information, explore our article explaining debugging in software development .

3. NuGet package support

Simple C# programs often work without external dependencies. More complicated examples may require third party packages.

.NET Fiddle and JDoodle both document support for compatible NuGet packages.

However, package integration does not guarantee that every library will work.

Some packages require system level functionality, native dependencies or configurations unavailable in hosted execution environments.

4. Project complexity

Online compilers are convenient for experimenting with individual functions, testing algorithms and executing short programs.

However, developing larger applications may require multiple source files, external dependencies, persistent storage and extensive debugging.

When these requirements become important, consider a project oriented environment or a locally installed development tool.

Explore our guide to C# IDEs and code editors for additional development options.

5. Registration and pricing

Some online compilers allow users to execute code immediately, while others require registration.

For example, JDoodle advertises registration-free code execution but requires an account for saving projects and accessing certain additional capabilities. Replit's C# environment currently directs users to sign up. Check each provider's current pricing and resource limits before relying on its services for substantial projects.

Online C# compiler vs. local C# IDE

Although online compilers eliminate many initial setup requirements, they do not provide every capability available in locally installed development environments.

Online compilers are convenient for learning and experimentation. Local development environments provide greater control over complex projects, system integrations and development configurations.

Many programmers use both approaches depending on their requirements.

Common limitations of online C# compilers

Online compilers offer convenience, but users should understand their limitations before relying on them.

Restricted execution resources: Platforms may impose limits on memory, CPU usage and execution time. Programs involving extensive computation might exceed these limits.

Limited operating system access: Hosted execution environments may restrict file operations, network access and operating-system integration.

Runtime compatibility: Some platforms use older Mono environments or offer only a limited range of runtime versions.

External dependency restrictions: Not every compiler supports NuGet packages, native dependencies or complicated project configurations.

Internet dependency: Most online compilers execute code on remote infrastructure and require an active internet connection.

Privacy considerations: Avoid uploading confidential source code, passwords, API keys and proprietary information without reviewing the provider's security and data handling practices.

These limitations are particularly important when moving beyond basic programming exercises.

Conclusion

Online C# compilers offer a convenient way to practice programming, test code and experiment with .NET technologies without configuring a local development environment.

The 12 platforms discussed in this article serve different requirements. Some emphasize learning and simple execution, while others provide runtime selection, package integration, compilation analysis or broader cloud development capabilities.

Before choosing a platform, consider your programming experience, required C# version, debugging needs and project complexity.

Using an online compiler alongside a local development environment can also be an effective approach, allowing you to experiment quickly while maintaining larger projects with professional development tools.