OpenRewrite vs PolyglotPiranha

OpenRewrite is an open-source ecosystem for automated code refactoring, aimed at updating code and reducing technical debt. It represents code as Lossless Semantic Trees, applies transformations, and prints the result back into source code for review. Its recipes cover framework migrations, security fixes, and style consistency, and can be written in YAML, Refaster templates, or Java. Maven and Gradle plugins run recipes locally as part of builds, one repository at a time. The Maven plugin offers a dry run that reports potential changes and writes diff files; recipes run only when explicitly activated by name. Documented support includes Java, Kotlin, and Groovy, plus formats such as HCL, JSON, Properties, Protobuf, TOML, XML, and YAML. Framework coverage includes Spring, Quarkus, and Micronaut. The recipe index lists 4,183 recipes across modules. Core and language libraries use Apache License 2.0, but some recipes have other licensing terms. Core is free; some artifacts require authenticated repository access, and some recipes require a Moderne subscription.

PolyglotPiranha is a free, multilingual structural search-and-replace engine for code cleanup. It can refactor stale feature-flag code when given a flag name, expected behavior, and configured feature-flag API rules. Rules can form graphs, and built-in language-specific cleanups include simplifying boolean expressions and if-else statements, removing empty declarations and files, and inlining local variables. Queries and filters may use Tree-sitter queries, regular expressions, or Piranha’s concrete syntax. The project is available as a Python library and command-line tool, with the Python API wrapping the CLI. The CLI lists Java, Swift, Python, Kotlin, Go, TSX, and TypeScript as target languages. Dry runs prevent in-place rewriting and produce summaries of matches, rewrites, and resulting file content. API configuration requires code path, configuration path, target language, and substitutions, with optional rules.toml and edges.toml files. Python installation uses pip; the CLI can be built with Rust and Cargo or obtained from releases. Piranha is Apache 2.0, provided as is, and not an official Uber product.