rustfmt

rustfmt is the Rust code formatter that applies Rust style guidelines to files and Cargo projects. It suits Rust developers who want a shared format across local work, editors, and CI. Its free, open-source workflow is a strong fit for ordinary Rust code, but comments and some macro cases remain rough edges, and the latest version requires nightly.

Overview

Rustfmt can format files in place or take Rust code on standard input and return formatted output on standard output. For Cargo projects, cargo fmt formats the crate’s binary and library targets and works across workspaces, making it practical to apply one formatting convention across a project rather than invoke the formatter file by file.

The Rust Edition Guide describes a formatting stability guarantee intended to prevent noisy changes when updating the Rust toolchain. That matters for teams: formatting is most useful when it settles routine style decisions without turning a toolchain update into a broad diff.

Key features

Cargo and CI

Use cargo fmt --all -- --check in CI to fail a build when formatting changes are needed. In check mode, rustfmt exits with code 0 when no changes are needed and 1 when it would make changes. This gives teams a straightforward way to enforce formatting without having CI rewrite files.

Configuration and editors

Configuration goes in rustfmt.toml or .rustfmt.toml. Stable options suit teams that want customization without moving to nightly; unstable options require opt-in and a nightly toolchain. The README lists integrations for Vim, Emacs, Sublime Text 3, Atom, Visual Studio Code, IntelliJ, and CLion. IntelliJ and CLion can run formatting on save or through a shortcut.

One practical boundary is that rustfmt formats code containing comments but does not attempt to format the comments themselves. Its documented limitations also include some macro declarations and uses, unparsable code, code fragments, non-ASCII Unicode, and bugs, so projects with those cases should expect exceptions rather than assume every file will be handled uniformly.

Pricing

Rustfmt is free and open source, with a listed price of no cost. It is distributed under both the MIT License and Apache License 2.0. There is no paid plan or trial to weigh against the free offering.

Platforms

Rustfmt supports Windows, macOS, and Linux. It is a Rust formatter, not a multi-language tool. The README says it runs with Rust 1.24 and above, while the latest version requires the nightly toolchain; stable-toolchain installation is documented with rustup component add rustfmt. That makes stable rustfmt the simpler route for users who do not need nightly-only configuration, while those seeking the latest version must accept the nightly dependency.

Who it's for

Rustfmt is the natural choice for Rust developers who want formatting integrated with Cargo, editor workflows, or a CI check, especially when the team values a consistent style and predictable diffs. It is less suitable as a comments formatter or for codebases that rely heavily on macro forms or other documented limitations. Developers who cannot use nightly should also weigh whether the stable toolchain meets their needs.

Pros and cons

• Pro: Cargo and workspace support makes project-wide formatting practical.
• Pro: CI check mode reports needed changes with a nonzero exit code, so teams can enforce formatting without rewriting files in the build.
• Pro: Configuration files and a broad set of editor integrations support both personal and team workflows.
• Con: Comments themselves are not formatted, so rustfmt does not solve all source-layout cleanup.
• Con: Some macro cases and other documented limitations can prevent uniform handling across a codebase.
• Con: The latest version requires nightly, and unstable settings require nightly plus opt-in.

Alternatives

For a broader set of code-formatting choices, browse Code Formatting Tools.

Pick Black for Python formatting, Prettier for web-oriented formatting, or gofmt for Go; each is a free formatter for a different language or project focus. dprint is another free, MIT-licensed CLI with self-managed installation, while Biome is a free open-source toolchain for web projects. Consider Ruff for Python tooling, or Taplo for TOML. Accessibility Test Framework for Android is another free option, with Android, Linux, macOS, and Windows support.

Verdict

Choose rustfmt if you work in Rust and want a free formatter that fits Cargo, editors, and CI, with a stability guarantee aimed at keeping toolchain updates from producing noisy formatting changes. Look elsewhere if formatting comments or reliably covering your project’s macro-heavy code is central, or if you need the latest version but cannot use nightly.