Kotlin Formatter

The Kotlin Formatter is an online tool that enforces a single, canonical formatting style for Kotlin source code. It targets developers, code maintainers, educators, and teams seeking consistency across files and pull requests. The service is stateless and operates on text input, returning formatted Kotlin code without altering semantics. It preserves comments and string literals, ensuring intent is unchanged while whitespace and structure are standardized. It handles common constructs such as classes, functions, lambdas, data classes, and multiline strings, applying consistent indentation, brace placement, and line breaks. The result is immediately usable in repositories, reviews, or teaching materials.

Conceptually, the formatter follows a token-aware approach: it parses Kotlin source, applies a set of canonical style rules, and rewrites only whitespace, line breaks, and brace positioning. Output is deterministic: formatting an already formatted file yields the same text. It operates without performing semantic analysis or code modification, so identifiers, logic, and behavior are preserved. The tool supports formatting entire files or selected regions, and the output remains valid Kotlin source ready for paste into editors or CI pipelines. Optional integration points allow supplying preferences such as indentation width and wrapping behavior where supported.

Users include individual developers, teams enforcing shared conventions, educators grading student submissions, and CI workflows that fail on formatting diffs. The tool's unique value lies in speed, reliability, and ease of use: no installation is required, instant feedback is provided, and formatted output can be copied or saved for immediate use in version control or documentation. By separating formatting from analysis, teams reduce review friction and ensure a uniform code appearance across projects.