Comparison

There are three CMake formatters in active use: cmakefmt, cmake-format, and gersemi. This page summarises the key differences to help you choose.

At a Glance

Feature	cmakefmt	cmake-format	gersemi
Command specs	150+ (CMake 4.3)	~100 (CMake 3.20)	Built-in
Active maintenance	Yes	No (last release 2021)	Yes
Recursive discovery	By default	No (explicit file list)	By default
Parallel formatting	By default	No	No
Language	Rust	Python	Python
Install	Homebrew, cargo, pip, conda, binary	pip	pip
LSP server	Built-in (cmakefmt lsp)	No	No
VS Code extension	First-party	First-party	No
Watch mode	--watch	No	No
Check mode	--check	--check-only	--check
Diff output	--diff	No	No
Git-aware selection	--staged, --changed	No	No
Range formatting	--lines	No	No
GitHub Action	cmakefmt/cmakefmt-action	No	No
CI report formats	GitHub, Checkstyle, JUnit, SARIF, JSON	No	No
Config file	YAML or TOML	Python, YAML, or JSON	None
Config discovery	Per-file, walks up to .git root	Directory-based	None
Config autocomplete	JSON Schema on SchemaStore	No	No
Migrate existing config	cmakefmt config convert	—	—
Parse tree dump	cmakefmt dump ast/parse	--dump parse	No
Stdin formatting	--stdin-path <path> -	via --	via stdin
License	MIT OR Apache-2.0	Apache-2.0	MIT

File Discovery and Parallelism

cmakefmt recursively discovers all CMakeLists.txt and *.cmake files by default — just point it at your project root. It also formats them in parallel using all available CPUs. On a 611-file repository this means sub-second formatting of the entire project.

cmake-format requires you to pass every file explicitly (or write a find + xargs wrapper). It has no parallel mode.

gersemi supports recursive discovery but has no parallel mode.

Performance

cmakefmt is a native binary with no interpreter startup overhead. On a cold invocation it formats a typical CMakeLists.txt in under 10 ms. Python tools (cmake-format, gersemi) typically spend 200–500 ms just starting the interpreter before any file is touched — noticeable on every save in an editor.

For large repositories cmakefmt also ships a content-addressed cache (--cache) so unchanged files are not re-parsed between runs.

See Performance for full benchmarks.

Configuration

cmakefmt supports YAML and TOML config files (.cmakefmt.yaml, .cmakefmt.toml) with a structured, documented schema. Config is discovered automatically by walking up from the file being formatted to the filesystem root, mirroring how tools like rustfmt and ruff work.

cmakefmt also publishes a JSON Schema to SchemaStore, which means editors with YAML language support (VS Code with the Red Hat YAML extension, JetBrains IDEs, Neovim with yaml-language-server) automatically provide autocomplete, validation, and inline documentation for .cmakefmt.yaml — no per-user setup required.

cmake-format supports a wider variety of config formats (Python files, YAML, JSON) but has no schema and no autocomplete support. gersemi has no config file at all — its formatting is entirely opinionated.

Editor Integration

cmakefmt ships a first-party VS Code extension (cmakefmt.vscode-cmakefmt) with format-on-save support. It works in Neovim via conform.nvim, Helix, Zed, and Emacs via apheleia — see the Editor Integration page.

cmake-format has a widely-used VS Code extension with over 500k installs. gersemi has no editor integration.

CI and Automation

cmakefmt ships a first-party GitHub Action (cmakefmt/cmakefmt-action) that installs the right binary for the runner OS in one uses: line — see the CI Integration page. It also outputs GitHub Actions annotations via --report-format github, Checkstyle XML, JUnit XML, and SARIF JSON for downstream tooling.

Neither cmake-format nor gersemi ship a GitHub Action.

Maintenance Status

cmake-format last released in 2021 and is in maintenance-only mode. The Python 3 ecosystem has moved on and there are known compatibility issues with newer Python versions. gersemi is actively maintained. cmakefmt is under active development with frequent releases.

Migrating from cmake-format

cmakefmt can convert your existing cmake-format config automatically:

cmakefmt config convert .cmake-format.yaml > .cmakefmt.yaml

See the Migration Guide for a full walkthrough.