C# Code Formatter

A C# formatter for .NET code

This C# formatter uses clang-format's C# mode, running as WebAssembly in your browser. It lays out classes, records, properties, lambdas, LINQ chains and attributes according to a style preset. The default Microsoft preset is closest to the conventions used across the .NET ecosystem: every brace on its own line (Allman style) and 4-space indentation.

Example

public class OrderService{private readonly IRepo _repo;public OrderService(IRepo repo)=>_repo=repo;public async Task<IEnumerable<Order>> RecentAsync(int days){var since=DateTime.UtcNow.AddDays(-days);return (await _repo.AllAsync()).Where(o=>o.Created>since).OrderByDescending(o=>o.Created);}public string Name{get;set;}}

public class OrderService
{
    private readonly IRepo _repo;
    public OrderService(IRepo repo) => _repo = repo;
    public async Task<IEnumerable<Order>> RecentAsync(int days)
    {
        var since = DateTime.UtcNow.AddDays(-days);
        return (await _repo.AllAsync())
            .Where(o => o.Created > since)
            .OrderByDescending(o => o.Created);
    }
    public string Name { get; set; }
}

The expression-bodied constructor stays on one line, the LINQ chain wraps before each dot, and the auto-property is printed as { get; set; } with spaces inside the braces.

C# conventions the Microsoft preset follows

• Allman braces for namespaces, types, methods and control statements, as in the .NET runtime and most Microsoft documentation samples.
• 4 spaces per indent level, no tabs.
• Spaces around binary operators, after commas and after keywords like if and foreach.
• 120-column guideline in the preset; this tool starts at 100, which you can raise.

One difference from Visual Studio defaults: with a block-scoped namespace X { }, the Microsoft preset does not indent the types inside the namespace. File-scoped namespaces (namespace X;), common since C# 10, avoid the question entirely.

Other presets

If your team prefers K&R braces (opening brace at the end of the line), choose Google, LLVM or Chromium; these produce 2-space indentation unless you set Indent to 4. Unity projects often use Allman braces as well, so the Microsoft preset works for most game scripts.

What is formatted

• Classes, structs, interfaces, records (public record Order(int Id, decimal Total);) and enums.
• Properties, indexers, events, expression-bodied members and local functions.
• Lambdas, LINQ method syntax, async/await and using statements.
• Attributes like [HttpGet("{id}")], generics with constraints, and nullable annotations (string?).
• Interpolated strings ($"Hello {name}") and verbatim strings are kept verbatim.

Limits of clang-format for C#

clang-format does not parse C# the way the Roslyn compiler does. It will not reorder using directives by System-first rules, apply naming conventions, or add braces to single-line if statements. Very new syntax, such as collection expressions or some pattern-matching forms, may be spaced conservatively. For project-wide enforcement, dotnet format with an .editorconfig is the standard .NET tool; this page is ideal for quickly tidying a snippet, a Stack Overflow answer or generated code.

Common problems

• Everything after a point is mis-indented: usually an unbalanced brace or an unterminated string. clang-format does not report syntax errors, so the odd indentation is your hint.
• Preprocessor directives such as #if DEBUG and #region / #endregion are kept at the start of the line, and the code between them is indented normally.
• XML doc comments (/// <summary>) are kept; long ones are not re-wrapped.

To create C# classes from an API response, try JSON to C#. To escape text for a C# string literal, use .NET Escape. All formatting happens locally in your browser.