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This is a mode for editing C# in emacs. It’s using CC mode or tree-sitter for highlighting and indentation.

Main features

  • font-lock and indent of C# syntax including:
    • all c# keywords and major syntax
    • attributes that decorate methods, classes, fields, properties
    • enum types
    • #if/#endif #region/#endregion
    • instance initializers
    • anonymous functions and methods
    • verbatim literal strings (those that begin with @)
    • generics
  • intelligent insertion of matched pairs of curly braces.
  • compilation-mode support for msbuild, devenv and xbuild.

tree-sitter support

You can enable experimental tree sitter support for indentation and highlighting using

(use-package tree-sitter :ensure t)
(use-package tree-sitter-langs :ensure t)
(use-package tree-sitter-indent :ensure t)

(use-package csharp-mode
  :ensure t
  (add-to-list 'auto-mode-alist '("\\.cs\\'" . csharp-tree-sitter-mode)))

If you are using this, clearly state so if you find any issues.

Note that we don’t depend on tree-sitter yet, so you have to manually install the packages involved. The simplest way is to use the provided snippet above.

Using and evolving the tree-sitter functionality.

tree-sitter introduces a minor mode called tree-sitter-debug-mode where you can look at the actual syntax tree it produces. If and when you spot missing or wrong syntax highlighting, look at how the patterns are written in csharp-tree-sitter-mode.el, then submit a pr with a couple new ones added. When testing and debugging this, it is actually as simple as M-x eval-buffer on csharp-tree-sitter-mode.el, then M-x revert-buffer in the file you are testing. It should update and show the correct syntax highlighting.

So the development cycle is:

  • Spot missing syntax highlighting
  • View AST with tree-sitter-debug-mode
  • Locate offending part
  • Add new pattern
  • M-x eval-buffer in csharp-tree-sitter-mode.el
  • M-x revert-buffer inside your some-test-file.cs


This package is currently available on both ELPA and MELPA. Install using M-x package-install<RET>csharp-mode.

Once installed the package should be automatically used for files with a ‘.cs’-extension.

Note: This package is also available on MELPA-stable for those who don’t want or need bleeding edge development-versions.

For a better experience you may want to enable electric-pair-mode when editing C#-files. To do so, add the following to your .emacs-file:

(defun my-csharp-mode-hook ()
  ;; enable the stuff you want for C# here
  (electric-pair-mode 1)       ;; Emacs 24
  (electric-pair-local-mode 1) ;; Emacs 25
(add-hook 'csharp-mode-hook 'my-csharp-mode-hook)

For further mode-specific customization, M-x customize-group RET csharp RET will show available settings with documentation.

For more advanced and IDE-like functionality we recommend using csharp-mode together with lsp-mode or eglot


This repo was a fork of the code originally developed by Dylan R. E. Moonfire and further maintained by Dino Chiesa as hosted on Google code.

New focus

The original csharp-mode repo contained lots of different code for lots of different purposes, some finished, some not, some experimental, some not. Basiaclly things like ASPX-mode, TFS-mode, code completion backends, etc.

All this original code can still be found in the extras-branch, but we have decided to go for a more focused approach and to throw out all dead or unused code, code we wont be maintaining.

The goal: That what we package in csharp-mode actually works and works well.


This package aims to stay as close to mainline emacs as it can. As such, paperwork with the FSF is needed for contributions of significant size.


The original project was licensed under GPL v2+, but after a rewrite in September 2020, it was relicensed to GPLv3+