swift-format

What swift-format is

swift-format is a free, open-source formatter and linter for Swift source code, also providing components for code-formatting transformations. Its format command processes one or more Swift files or Swift code read from standard input. The lint command checks Swift files for style violations and writes diagnostics to standard error. A JSON configuration file lets users customize supported behavior, and the tool searches parent directories for a .swift-format file. Swift applications can import the SwiftFormat package module, including SwiftFormatter and SwiftLinter APIs. Swift Package Manager command plugins provide formatting and linting operations, while SourceKit-LSP can use swift-format’s formatting technology. Installation is documented through the Swift toolchain, Homebrew, or a source build. The project README says Swift 6, included with Xcode 16, and later include swift-format in the toolchain. The repository identifies an Apache-2.0 license. Earlier releases may not understand syntax introduced by newer language and parser versions. The project describes its current style as one experimental possibility because no default Swift style guidelines have yet been proposed.

Who it suits

swift-format suits Swift developers who need command-line formatting, lint checks, configurable style behavior, or reusable formatting APIs. It also fits projects using Swift Package Manager plugins, SourceKit-LSP, or the Swift toolchain.

Limits

Earlier swift-format versions may not recognize syntax introduced by later language and parser versions. The project’s current style is an experimental possibility rather than a proposed default Swift style.

Getting started

1. Install through the Swift toolchain, Homebrew, or by building from source
2. Run the format command on Swift files or provide code through standard input
3. Run the lint command to print style diagnostics
4. Add a JSON configuration file to customize supported behavior
5. Use a .swift-format file in a parent directory for project settings
6. Add Swift Package Manager plugins or import the SwiftFormat module

Verdict

Choose swift-format for a free, Apache-2.0 tool that formats and lints Swift with command-line, plugin, API, and editor integration options. It is especially useful when you want configurable behavior or SourceKit-LSP support. Consider another approach if your code relies on syntax unsupported by the version you use or if you need an established default style standard.