Why not just Rider / ReSharper cleanup?

You do not have to choose. Curb reads the same .editorconfig keys Rider does, so if your repository already has a Rider configuration, that configuration works for Curb without a single change.

Rider uses several .editorconfig key families that are not part of the official IDE0055 surface but are documented by JetBrains and read by ReSharper:

csharp_wrap_parameters_style = chop_if_long
csharp_wrap_arguments_style = chop_if_long
csharp_wrap_object_and_collection_initializer_style = chop_if_long
csharp_wrap_before_first_method_call = true
csharp_wrap_before_arrow_with_expressions = false
csharp_place_simple_accessorholder_on_single_line = true
csharp_place_simple_enum_on_single_line = true
csharp_blank_lines_around_invocable = 1
csharp_blank_lines_around_type = 1
csharp_trailing_comma_in_multiline_lists = true
		

Curb honours all of them. The defaults leave everything off — so a repository that never set them is unchanged — and a repository that set them for Rider gets the same layout from Curb.

dotnet format does not read any of these keys. If you want wrapping and blank-line rules from your .editorconfig enforced consistently across the command line, the build, and CI, Curb is currently the only way to do that.

Rider's cleanup can apply semantic fixes: unused imports, var where the type is apparent, naming conventions, null-check simplifications. These need to know what a name means, which requires a full project load.

Curb does not do any of that. It covers what syntax alone can decide — layout, brace style, modifier order, expression bodies, file-scoped namespaces, using placement. Everything that requires a compilation stays with Rider's cleanup and dotnet format style.

That scope boundary is what makes Curb fast enough to run inside every build.

Rider cleanup runs when a developer explicitly invokes it. Curb runs on every dotnet build. The two cover different moments: Rider catches things in the editor, Curb enforces them in the build so CI never sees a mechanically unformatted commit.

They also cover different keys. A team that uses both gets consistent style whether someone formatted via the IDE or via the command line.