Editor Integration

cmakefmt works with every editor in two ways:

1. LSP server (cmakefmt --lsp) — the recommended approach for editors with LSP client support. Provides format-on-save and range formatting with no extra plugins.
2. Stdin pipe (cmakefmt --stdin-path <file> -) — works with any editor that supports external formatters.

Install cmakefmt once, then drop the config snippet for your editor below.

VS Code

Install the official extension from the VS Code Marketplace:

• Extension ID: cmakefmt.vscode-cmakefmt
• Marketplace: cmakefmt — VS Code Marketplace

The extension formats on save by default and uses whichever cmakefmt binary is on your PATH. To customise, add any of the following to your .vscode/settings.json:

{
  "cmakefmt.executablePath": "cmakefmt",
  "cmakefmt.extraArgs": [],
  "cmakefmt.onSave": true
}

Setting	Default	Description
cmakefmt.executablePath	"cmakefmt"	Path to the cmakefmt binary
cmakefmt.extraArgs	[]	Extra flags, e.g. ["--config", "/path/to/.cmakefmt.yaml"]
cmakefmt.onSave	true	Format CMake files automatically on save

Neovim

Option A: LSP (recommended)

Add cmakefmt as a language server via nvim-lspconfig:

vim.api.nvim_create_autocmd("FileType", {
  pattern = "cmake",
  callback = function()
    vim.lsp.start({
      name = "cmakefmt",
      cmd = { "cmakefmt", "--lsp" },
    })
  end,
})

-- Format on save
vim.api.nvim_create_autocmd("BufWritePre", {
  pattern = { "CMakeLists.txt", "*.cmake" },
  callback = function()
    vim.lsp.buf.format({ timeout_ms = 2000 })
  end,
})

Option B: conform.nvim

Use conform.nvim — the standard Neovim formatter plugin. Add cmakefmt as a custom formatter and associate it with the cmake filetype:

require("conform").setup({
  formatters_by_ft = {
    cmake = { "cmakefmt" },
  },
  formatters = {
    cmakefmt = {
      command = "cmakefmt",
      args = { "--stdin-path", "$FILENAME", "-" },
      stdin = true,
    },
  },
  format_on_save = {
    timeout_ms = 2000,
    lsp_fallback = false,
  },
})

The $FILENAME argument lets cmakefmt discover the nearest .cmakefmt.yaml config relative to the file being formatted.

Helix

Option A: LSP (recommended)

Add cmakefmt as a language server in ~/.config/helix/languages.toml:

[language-server.cmakefmt]
command = "cmakefmt"
args = ["--lsp"]

[[language]]
name = "cmake"
language-servers = ["cmakefmt"]
auto-format = true

Option B: External formatter

[[language]]
name = "cmake"
formatter = { command = "cmakefmt", args = ["-"] }
auto-format = true

Helix invokes the formatter from the project root, so cmakefmt will discover your .cmakefmt.yaml automatically. The - argument tells cmakefmt to read from stdin.

Zed

Option A: LSP (recommended)

Add cmakefmt as a language server in ~/.config/zed/settings.json:

{
  "lsp": {
    "cmakefmt": {
      "binary": { "path": "cmakefmt", "arguments": ["--lsp"] }
    }
  },
  "languages": {
    "CMake": {
      "language_servers": ["cmakefmt"],
      "format_on_save": "on"
    }
  }
}

Option B: External formatter

{
  "languages": {
    "CMake": {
      "formatter": {
        "external": {
          "command": "cmakefmt",
          "arguments": ["--stdin-path", "{buffer_path}", "-"]
        }
      },
      "format_on_save": "on"
    }
  }
}

Zed substitutes {buffer_path} with the actual file path at format time, which enables config discovery.

Emacs

With apheleia:

(require 'apheleia)

(add-to-list 'apheleia-formatters
             '(cmakefmt . ("cmakefmt" "--stdin-path" filepath "-")))

(add-to-list 'apheleia-mode-alist
             '(cmake-mode . cmakefmt))

(apheleia-global-mode +1)

Apheleia replaces filepath with the path of the buffer being formatted.

Any other editor

If your editor has an LSP client, point it at:

cmakefmt --lsp

This provides format-on-save and range formatting over the standard Language Server Protocol (JSON-RPC on stdio).

If your editor does not support LSP but does support external formatters, use the stdin pipe approach:

cmakefmt --stdin-path <current-file-path> -

Pipe the buffer contents to stdin and read the formatted output from stdout. The --stdin-path argument is optional but recommended — it tells cmakefmt which file the input corresponds to so it can discover the right config file and apply the correct ignore rules.

If your editor does not support passing the file path to the formatter, omit --stdin-path and cmakefmt will fall back to config discovery from the current working directory.