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title Formatters
description OpenCode uses language specific formatters.

OpenCode can format files after they are written or edited using language-specific formatters. Formatters are disabled by default; enable them in your config before OpenCode will run them.

Built-in

OpenCode comes with several built-in formatters for popular languages and frameworks. Below is a list of the formatters, supported file extensions, and commands or config options it needs.

Formatter Extensions Requirements
air .R air command available
biome .js, .jsx, .ts, .tsx, .html, .css, .md, .json, .yaml, and more biome.json(c) config file
cargofmt .rs cargo fmt command available
clang-format .c, .cpp, .h, .hpp, .ino, and more .clang-format config file
cljfmt .clj, .cljs, .cljc, .edn cljfmt command available
csharpier .cs dotnet-csharpier command available
dart .dart dart command available
dfmt .d dfmt command available
gleam .gleam gleam command available
gofmt .go gofmt command available
htmlbeautifier .erb, .html.erb htmlbeautifier command available
ktlint .kt, .kts ktlint command available
mix .ex, .exs, .eex, .heex, .leex, .neex, .sface mix command available
nixfmt .nix nixfmt command available
ocamlformat .ml, .mli ocamlformat command available and .ocamlformat config file
ormolu .hs ormolu command available
oxfmt (Experimental) .js, .jsx, .ts, .tsx oxfmt dependency in package.json and an experimental env variable flag
pint .php laravel/pint dependency in composer.json
prettier .js, .jsx, .ts, .tsx, .html, .css, .md, .json, .yaml, and more prettier dependency in package.json
rubocop .rb, .rake, .gemspec, .ru rubocop command available
ruff .py, .pyi ruff command available with config
rustfmt .rs rustfmt command available
scalafmt .scala scalafmt command available and .scalafmt.conf config file
shfmt .sh, .bash shfmt command available
standardrb .rb, .rake, .gemspec, .ru standardrb command available
stylua .lua stylua command available
swiftformat .swift swiftformat command available
terraform .tf, .tfvars terraform command available
typst .typ, .typc typst command available
uv .py, .pyi uv command available
zig .zig, .zon zig command available

When formatters are enabled, OpenCode will use prettier for matching files if your project has prettier in package.json.

How it works

When OpenCode writes or edits a file and formatters are enabled, it:

  1. Checks the file extension against all enabled formatters.
  2. Runs the appropriate formatter command on the file.
  3. Applies the formatting changes.

This process happens in the background for enabled formatters.

Configure

You can enable and customize formatters through the formatter section in your OpenCode config.

To enable all built-in formatters, set formatter to true.

{
  "$schema": "https://opencode.ai/config.json",
  "formatter": true
}

Use an object to keep built-ins enabled while configuring overrides or custom formatters.

{
  "$schema": "https://opencode.ai/config.json",
  "formatter": {}
}

Each formatter configuration supports the following:

Property Type Description
disabled boolean Set this to true to disable the formatter
command string[] The command to run for formatting. Required for custom formatters; optional for built-ins.
environment object Environment variables to set when running the formatter
extensions string[] File extensions this formatter should handle

Let's look at some examples.

Disabling formatters

If formatter is omitted, all formatters are disabled. To disable all formatters after another config enabled them, set formatter to false:

{
  "$schema": "https://opencode.ai/config.json",
  "formatter": false
}

To disable a specific formatter, set disabled to true:

{
  "$schema": "https://opencode.ai/config.json",
  "formatter": {
    "prettier": {
      "disabled": true
    }
  }
}

Custom formatters

You can configure built-in formatters with options like environment or extensions. To add a custom formatter, specify a command and extensions:

{
  "$schema": "https://opencode.ai/config.json",
  "formatter": {
    "prettier": {
      "command": ["npx", "prettier", "--write", "$FILE"],
      "environment": {
        "NODE_ENV": "development"
      },
      "extensions": [".js", ".ts", ".jsx", ".tsx"]
    },
    "custom-markdown-formatter": {
      "command": ["deno", "fmt", "$FILE"],
      "extensions": [".md"]
    }
  }
}

The $FILE placeholder in the command will be replaced with the path to the file being formatted.