Scalafmt

What Scalafmt is

Scalafmt is a free, open-source formatter for Scala code that helps teams apply consistent formatting. It handles Scala 2 and Scala 3, as well as sbt files and Scala scripts. Each file uses one selected dialect. Formatting options are kept in a plain text `.scalafmt.conf` file written in HOCON syntax; since version 3.1.0, configuration must explicitly state the version and `runner.dialect`. Scalafmt can run from an editor, a build tool, or a terminal. Documented editor integrations include IntelliJ, VS Code, Vim, NeoVim, Emacs, Sublime Text, and Eclipse, and Metals supports formatting requests from editors. For builds, it integrates with sbt and documents integrations for Maven, Gradle, and Mill. The command-line check and test modes identify misformatted code without writing changes. Additional capabilities include ignoring files, formatting changed lines, and using Scalafmt as a library. IntelliJ uses its own formatter for range formatting by default: Scalafmt is primarily designed for whole text files, and selected ranges may produce undesirable results. The project identifies its license as Apache-2.0. The project site links to community Discord and GitHub, and CLI help directs bug reports to GitHub issues.

Who it suits

Scalafmt suits Scala developers and teams who want formatting rules applied consistently through editors, builds, or the terminal. Its supported Scala dialects, build integrations, and check modes make it useful across different development workflows.

Getting started

1. Visit the Scalafmt project website.
2. Choose an editor, build tool, or terminal workflow.
3. Create a plain text `.scalafmt.conf` file using HOCON syntax.
4. Set the version and `runner.dialect` explicitly.
5. Run Scalafmt on Scala, sbt, or Scala script files.

Verdict

Choose Scalafmt if you need a free, open-source formatter for Scala projects and want to run it through editors, builds, or the command line. Its main caveat is IntelliJ range formatting, which defaults to IntelliJ’s formatter and may not suit Scalafmt’s whole-file approach.