Oxfmt: Oxc Formatter Alpha

• 

  BoshenProject Lead

• 

  DunqingCore

• 

  Yuji SugiuraCore

We’re excited to announce the alpha release of Oxfmt, a Rust-powered, Prettier-compatible code formatter. This first release focuses on JavaScript and TypeScript, with support for additional languages coming soon.

Oxfmt is designed with these goals in mind:

• Performance: More than 30× faster than Prettier and more than 3× faster than Biome on an initial run without a cache (benchmark).
• Compatibility: Prettier-compatible, so you can adopt Oxfmt in existing projects easily.
• Developer Experience: Upcoming features include import sorting, expanded formatting options, and support for Prettier plugins.

Quick Start

Add oxfmt to your project:

npm

$ npm add -D oxfmt@latest

pnpm

$ pnpm add -D oxfmt@latest

yarn

$ yarn add -D oxfmt@latest

bun

$ bun add -D oxfmt@latest

deno

$ deno add -D npm:oxfmt@latest

Oxfmt follows Prettier’s configuration format. If you are using Prettier with a JSON configuration file, you can rename it to .oxfmtrc.jsonc:

cp .prettierrc.json .oxfmtrc.jsonc

You can also start from this .oxfmtrc.jsonc configuration example:

{
  "$schema": "./node_modules/oxfmt/configuration_schema.json",
  // Use 80 if migrating from Prettier; 100 is the Oxfmt default!
  "printWidth": 80,
  "ignorePatterns": [] // Same as `.prettierignore`
}

Next, add oxfmt to your package.json scripts:

"scripts": {
  "format": "oxfmt"
}

Alternatively, refer to the installation guide for detailed instructions.

Performance

Oxfmt is incredibly fast. Our benchmark results on the Outline repository show:

• Over 30× faster than Prettier’s experimental CLI without cache
• Over 20× faster than Prettier using Oxc’s parser through @prettier/plugin-oxc
• Over 3× faster than Biome, another Rust-based formatter

For detailed benchmark setup, please refer to the following repository:

oxc-project/bench-formatter
https://github.com/oxc-project/bench-formatter

Design

The Oxc team prioritizes compatibility with existing ecosystems, making migrations straightforward, even for large codebases.

Code formatting results

Oxfmt matches Prettier’s JavaScript formatting. If you are migrating to Oxfmt today, you shouldn’t see any formatting differences compared to Prettier.

You might see minor differences when migrating from older versions of Prettier (See an example migration) because we identified areas in which Prettier’s formatting could be improved. We have been actively collaborating with the Prettier team by submitting bug reports and pull requests directly to Prettier. Many of these improvements landed in the recent Prettier 3.7 release.

Oxfmt currently passes around 95% of Prettier’s JavaScript and TypeScript tests, and we hope to work with the Prettier team to converge on formatting over time.

printWidth: 100 by default

We chose printWidth: 100 as the default line length instead of Prettier's 80. Our reasons include:

• TypeScript code tends to be longer than JavaScript due to type annotations.
• Import statements often contain many items.
• Larger screens provide more horizontal space.
• Results in slightly fewer LLM tokens.

While Oxfmt remains compatible with Prettier, it uses a different default print width of 100 characters. If you want to avoid large diffs when migrating from Prettier, explicitly set the print width to 80.

ignorePatterns

While Oxfmt supports .prettierignore, it also supports an ignorePatterns configuration option to consolidate all configuration into a single file.

Configuration

Prettier JSON configuration files are compatible with Oxfmt. In the simplest case, migrating your config looks like this:

cp .prettierrc.json .oxfmtrc.jsonc

If your editor supports the JSON language server, you can start with this minimal template after adding oxfmt to your devDependencies:

{
  "$schema": "./node_modules/oxfmt/configuration_schema.json",
  "ignorePatterns": []
}

While we don’t yet support all of Prettier’s configuration options in this alpha release, we do support the following major options: printWidth, tabWidth, useTabs, semi, singleQuote, quoteProps, jsxSingleQuote, trailingComma, bracketSpacing, objectWrap, bracketSameLine, arrowParens, endOfLine, andsingleAttributePerLine.

Check out all of the options in our documentation.

Terminal Output

Oxfmt's default behavior is equivalent to prettier . --write, providing the same UX as cargo fmt and producing no output. You can use --check to display formatting differences and enforce oxfmt usage in CI pipelines.

Beta Release Plans

Here are our plans for the beta release:

• Support more file formats - like .json files
• Add support for embedded language formatting - css in js or graphql in js
• Built-in sorting and aesthetics features, such as sort imports
• Prettier plugins
• Node.js API for Oxfmt
• Disable newline at the end of file
• --migrate prettier
• … and your feature requests

You can track our progress towards the beta release here:

Formatter Beta · Milestone #15 · oxc-project/oxc
https://github.com/oxc-project/oxc/milestone/15

We also plan to relax some of the formatting opinions in future versions.

Next Steps

See the full installation guide in the Oxfmt docs.

Reporting Issues

For formatting differences, please refer to https://github.com/oxc-project/oxc/discussions/14669. Additionally, known issues are distinguished by labels.

If you find any other issues, please create an issue with dedicated template on GitHub.

Join the Community

RFC: Formatter · oxc-project/oxc · Discussion #13608
https://github.com/oxc-project/oxc/discussions/13608

We welcome your feedback to help make Oxfmt even better!

Acknowledgements

Oxfmt builds on a fork of the biome_formatter infrastructure, and we’d like to thank the Biome team, especially @ematipico and @MichaReiser. We’d also like to thank the Prettier team and @fisker for collaborating with us on formatting compatibility.