Formatterit

Formatterit is a cross-language code and text formatter designed to apply consistent style rules across files. It can read from files or standard input and write formatted output to stdout or modify files in place, depending on configuration. Its aim is deterministic formatting to reduce diffs and merge conflicts, with changes driven by style files that describe language- and project-specific rules.

Core features include multi-language support, a library of selectable style guides (for example guides aligned with common language communities), and a pluggable rule system that allows custom formatting behaviors. It offers a command-line interface, an API for integration into editors and pipelines, and editor plugins. Output can be a reformatted file, a unified diff, or an in-place update. It supports streaming mode to handle large codebases efficiently.

Formatterit originated as an open-source project in the late 2010s, developed by the AtlasCode community to address inconsistent formatting across languages. The project released its first stable version in 2020 and has since added language packs and expanded customization options. It is distributed under an open-source license, with ongoing maintenance and community contributions.

Usage and reception: It is adopted in many continuous integration workflows and by developers who prefer centralized formatting policies. It competes with language-specific formatters and global tools, emphasizing configurability and repeatable outputs.

Limitations: quality depends on the quality of the configured style guides; some languages rely on dedicated formatters for the best results. Complex configurations can increase setup time, and performance may vary with repository size and rule complexity.

See also: code formatter, style guide, linting tool.