# Migrate from oxfmt to bun fmt

`bun fmt` reads your `.oxfmtrc.json` and prints what oxfmt 0.72 prints. In most projects you only change the command.

Start with `--doctor`. It shows what Bun will do with your config, and it doesn't format or write anything.

```sh terminal icon="terminal"
bun fmt --doctor
```

```txt
Using .oxfmtrc.json (oxfmt config)

    3 files are formatted natively

Still needed:   oxfmt (the "format" script runs it)
```

---

Change the scripts.

```json package.json icon="file-json"
{
  "scripts": {
    "format": "oxfmt", // [!code --]
    "format:check": "oxfmt --check", // [!code --]
    "format": "bun fmt", // [!code ++]
    "format:check": "bun fmt --check" // [!code ++]
  }
}
```

Flags and arguments stay the same. Change CI and Git hooks too.

If your script is called `fmt`, don't skip this: `bun fmt` runs a `fmt` script when `package.json` has one, so you'd still get oxfmt.

---

Check that nothing changes. With an oxfmt config, a run prints what oxfmt prints.

```sh terminal icon="terminal"
bun fmt --check
```

```txt
$ bun fmt --check
Checking formatting...

All matched files use the correct format.
Finished in 4ms on 3 files using 64 threads.
```

If you're on a version of oxfmt before 0.72, a few files change once, like when you upgrade oxfmt.

---

Run `--doctor` again. No script runs oxfmt anymore, so you can uninstall it.

```txt
You can remove: oxfmt
Not checked:    other tools' configs, CI files, Git hooks
```

```sh terminal icon="terminal"
bun remove oxfmt
```

No `.oxfmtrc.json`? Add one with `{}` in it first. Without a config file, the `oxfmt` dependency is how Bun knows to format like oxfmt and not like Prettier.

---

Bun reads everything oxfmt reads:

- `.oxfmtrc.json`, `.oxfmtrc.jsonc`, and `oxfmt.config.ts`, with `overrides` and `ignorePatterns`
- The `fmt` key of `vite.config.ts`, if you use vite-plus
- Every option, including `sortImports`, `sortPackageJson`, `sortTailwindcss`, and `jsdoc`
- `// oxfmt-ignore` and `// prettier-ignore` comments
- Every flag of oxfmt 0.72 except `--lsp` and `--migrate`

It also follows oxfmt's defaults: lines wrap at 100 columns, every `.gitignore` in the repository counts, TOML files are formatted, and `.prettierrc` is ignored.

---

Still have a `.prettierrc` next to `.oxfmtrc.json`? Bun uses `.oxfmtrc.json` and tells you so. Delete the one you no longer use, or pick one with `--config`.

```txt
note: Using .oxfmtrc.json. .prettierrc is ignored. Use --config to pick it.
```

---

Keep `oxfmt` if your editor's oxc extension uses it. `bun fmt` has no language server.

---

## Differences from oxfmt

If `bun fmt` and oxfmt 0.72 print different code, that's a bug. [Open an issue](https://github.com/oven-sh/bun/issues). These differences are intentional:

- **The output is oxfmt 0.72's**, whatever version you had installed.
- **No `--lsp` or `--migrate`.**
- **No Svelte.** With `svelte` in the config, Bun skips `.svelte` files and exits with code `2`. `--allow-unsupported` makes that a warning.
- **Errors and warnings are worded differently.**
- **An invalid TOML file is left alone**, with a warning. oxfmt rewrites the parts it can read.
- **A file that isn't valid UTF-8 is still formatted**, and the invalid bytes are kept. oxfmt exits with code `2`.
- **Where oxfmt's output changes what a file means, Bun's differs.** That's rare. In TOML oxfmt joins the lines of an inline table with a comment, which comments out the rest of the table. Bun keeps one entry per line.

---

See also:

- [`bun fmt`](/format)
- [Migrate from oxlint to bun lint](/guides/lint/migrate-from-oxlint)