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elm-format
What elm-format is
elm-format is a command-line formatter for Elm source code, applying rules based on the official Elm Style Guide. It can process one file or all Elm files in a directory, and the --yes option allows it to overwrite files. The README documents installation with npm install -g elm-format or a release binary. Run it from a directory containing elm.json or elm-package.json, or provide the corresponding Elm version option. Release 0.8.7 provides binaries for Linux, macOS, and Windows. Listed editor integrations include Atom, Light Table, Vim, Emacs, Visual Studio Code, Sublime Text, JetBrains IDEs, and TextMate; Prettier integration is also listed through prettier-plugin-elm. Approved editor plugins default to formatting Elm files when saved. The project says consistent formatting can make code easier to write, read, and maintain, while reducing team debates over style. elm-format is free, supports Elm only, and is open source under the BSD-3-Clause license.
Who it suits
It suits Elm developers and teams who want to format source files consistently from the command line or a listed editor. Its language support is limited to Elm.
What it does well
- Formats a file or all Elm files in a directory
- Can overwrite files with the --yes option
- Integrations listed for multiple editors and Prettier
- Binaries available for Linux, macOS, and Windows
What to know first
- Supports Elm only
- Requires an Elm version context or option
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| elm-format | Elm source formatting · command-line tool | Free |
As github.com lists them, read 8 Oct 2026. The maker's own page has the final word.
Getting started
- Install with npm install -g elm-format or download a release binary.
- Use a Linux, macOS, or Windows installation.
- Run it from a directory containing elm.json or elm-package.json, or pass the matching Elm version option.
- Choose a file or directory to format; use --yes to allow overwriting.
- Connect a listed editor integration or Prettier through prettier-plugin-elm if desired.
Verdict
elm-format offers a free way to apply consistent formatting to Elm source code, with command-line and editor workflows. Its scope is focused on Elm rather than multiple languages.
Questions
How much does elm-format cost?
It is free. The listed plan price is free.
Which operating systems does it support?
The 0.8.7 release provides binaries for Linux, macOS, and Windows.
Which programming language does elm-format support?
It formats Elm source code.
Is elm-format open source?
Yes. The repository identifies its license as BSD-3-Clause.
How can I install it?
The README documents installation with npm install -g elm-format or by downloading a release binary.
Does it integrate with editors?
The project lists integrations for Atom, Light Table, Vim, Emacs, Visual Studio Code, Sublime Text, JetBrains IDEs, and TextMate. It also lists Prettier integration through prettier-plugin-elm.
Facts from elm-format's own pages
- Command line
- The command line can format a single Elm file or all Elm files in a directory, and can overwrite files with the --yes option. · github.com, 8 Oct 2026
- Consistent style
- The project says consistent formatting can make code easier to write, read, and maintain, and reduce team debates about formatting. · github.com, 8 Oct 2026
- Editor integrations
- The README lists integrations for Atom, Light Table, Vim, Emacs, Visual Studio Code, Sublime Text, JetBrains IDEs, and TextMate. · github.com, 8 Oct 2026
- Elm versions
- The README says to run elm-format from a directory containing elm.json or elm-package.json, or pass the corresponding Elm version option. · github.com, 8 Oct 2026
- Format on save
- The README says the default behavior of elm-format-approved plugins is to format Elm files on save. · github.com, 8 Oct 2026
- Install
- The README documents installation with npm install -g elm-format or by downloading a release binary. · github.com, 8 Oct 2026
- Intended users
- The README describes benefits for developers and teams writing and maintaining Elm code. · github.com, 8 Oct 2026
- License
- The repository identifies its license as BSD-3-Clause. · github.com, 8 Oct 2026
- Operating systems
- The 0.8.7 release provides binaries for Linux, macOS, and Windows. · github.com, 8 Oct 2026
- Other tool integration
- The README lists integration with Prettier through prettier-plugin-elm. · github.com, 8 Oct 2026
- Purpose
- elm-format formats Elm source code according to rules based on the official Elm Style Guide. · github.com, 8 Oct 2026
- Release
- The latest release page opened is version 0.8.7, released on April 11, with fixes and improvements including a Windows npm installer fix. · github.com, 8 Oct 2026
- Signing
- The 0.8.7 release page says its tag was signed with a verified committer signature and that the signing key has expired. · github.com, 8 Oct 2026
Where elm-format stands on Freedom251
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