OpenRewrite

OpenRewrite is a recipe-driven refactoring toolkit for teams maintaining Java, Kotlin, or Groovy code in Maven or Gradle repositories. It is most useful when migrations, security updates, or style changes must be repeatable and reviewable. The free core is compelling for repository-level work, but authenticated artifact access, mixed recipe licenses, and single-repository execution narrow its fit for larger programs.

Overview

OpenRewrite converts source into Lossless Semantic Trees, applies a recipe, and prints the changed tree back as source code. That structure-aware approach is better suited to broad, consistent edits than search-and-replace, particularly for framework migrations, security fixes, and stylistic cleanup. Java remains the original focus, while the project is expanding its language and framework coverage.

The recipe index contains 4,183 recipes across modules. Named framework coverage includes Spring, Quarkus, and Micronaut. Teams can write recipes as declarative YAML, Refaster templates, or imperative Java, so the system can support both ready-made maintenance and organization-specific transformations.

Key features

• Maven and Gradle integration: Plugins run recipes within a build, making refactoring part of an existing engineering workflow rather than a separate desktop process. Local execution does not connect to Moderne or OpenRewrite, except when retrieving artifacts from configured repositories.
• Review before applying: Maven's dry-run goal identifies recipes that would change files and writes diff files in each module's target directory. That gives reviewers a concrete checkpoint before source files are altered.
• Explicit recipe activation: Maven runs no recipe until one is activated by name. This avoids accidental broad changes, but it also puts selection and configuration responsibility on the team.
• Broad source support: The project documents Java, Kotlin, and Groovy, plus HCL, JSON, Properties, Protobuf, TOML, XML, and YAML formats. This is useful for changes that span code and configuration, although language and framework depth is not uniform.
• IDE and community help: IntelliJ IDEA 2024.1 or later has built-in OpenRewrite support, with the OpenRewrite IntelliJ plugin recommended. A free self-paced introductory course and Slack or Discord communities provide entry points for learning and troubleshooting.
• AST-based, batch refactoring: Core analysis is AST-based and supports batch changes within a repository. OpenRewrite itself processes one repository at a time; coordinated multi-repository execution belongs to Moderne.

Pricing

OpenRewrite core — free. This includes the core framework and Apache-licensed recipes, with execution limited to one repository at a time. It is the right starting point for individuals and teams that can work within Maven or Gradle and need open-source, repository-level automation.

The core software is open source, but “free” does not mean every recipe is unrestricted. Core framework and language libraries use Apache License 2.0, while some recipes are source-available or proprietary. Artifacts are distributed through the Code Genome Project repository, which requires authentication, and some source-available or proprietary recipes require a Moderne subscription. Source-available terms allow companies to apply that software to their own code but restrict commercialization or providing it to others as a managed service. Open-source projects may use Apache-licensed and Moderne Source Available recipes through the plugins or Moderne CLI without a license for those repositories.

Platforms

OpenRewrite is listed for Linux and self-hosted deployment. Maven and Gradle plugins fit build environments, and IntelliJ IDEA 2024.1 or later adds editor integration. The plugins operate locally, subject to configured artifact repositories, which suits organizations that keep source processing inside their own build infrastructure.

Who it's for

Choose OpenRewrite when your team needs repeatable migrations or maintenance across a Java-, Kotlin-, or Groovy-based repository and wants proposed changes represented as diffs before adoption. It is particularly suitable for Spring, Quarkus, or Micronaut projects and for groups willing to author or tailor recipes.

Look elsewhere when the requirement is coordinated change across many repositories, because the standalone tooling handles one repository at a time. Teams that need a fully permissive license for every recipe, or that cannot authenticate to the artifact repository, should also evaluate alternatives before committing.

Pros and cons

Pros

• Free core: The framework and Apache-licensed recipe set cost nothing, lowering the barrier to automated modernization.
• Reviewable workflow: Maven dry runs and generated diffs let teams inspect proposed edits before applying them.
• Large recipe catalog: 4,183 recipes and named support for major JVM frameworks provide substantial starting coverage.
• Build-native operation: Maven and Gradle plugins keep refactoring close to established build and CI processes.

Cons

• One-repository scope: Fleet-wide coordination requires Moderne rather than the standalone project.
• License variation: Some recipes are source-available or proprietary, with commercial and managed-service restrictions.
• Authenticated access: Code Genome Project distribution requires repository authentication, and selected recipes require a Moderne subscription.
• Activation overhead: No Maven recipe runs until explicitly named, so teams must manage recipe selection carefully.

Alternatives

Code Refactoring Tools is the broader category guide for comparing refactoring products. ast-grep is a free option spanning API, extensions, Linux, macOS, web, and Windows. CodeRush offers free commercial use with the same features and updates across its free and paid subscriptions. ReSharper suits users wanting a freemium extension with a non-commercial free plan and paid commercial edition. Roslynator provides free tools and extensions with donations welcomed. Coccinelle is a free Linux and macOS choice. CodART is MIT-licensed, though SciTools Understand needs a separate professional license. Sourcery offers a free open-source plan for public repositories with AI reviews, summaries, diagrams, one-click fixes, and custom rules. Spoon is free and open source with no paid plans or usage limits stated.

Verdict

OpenRewrite is a strong recommendation for JVM teams that want build-integrated, AST-based migrations and can review changes repository by repository. Its free core, dry-run diffs, and extensive recipe catalog are the main reasons to choose it. Look elsewhere if you need multi-repository orchestration, universally permissive recipe licensing, or an artifact workflow that does not require authentication.