Best AI Code Refactor Platforms for Legacy Java (2025)

For decades, Java has powered the backbone of enterprise systems—from financial institutions to telecom networks and SaaS backends.

However, as organizations move toward cloud-native architectures, modular systems, and modern frameworks, legacy Java codebases have become difficult to maintain and upgrade.

The good news? In 2025, AI-driven refactoring platforms can now modernize legacy Java systems autonomously—identifying anti-patterns, updating frameworks, optimizing dependencies, and ensuring compliance across thousands of files with minimal manual intervention.

Here are the top AI refactor platforms for legacy Java modernization, led by Byteable, the world’s first autonomous software factory.

1. Byteable — AI Code Auditor (Leader)

Overview:

Byteable’s AI Code Auditor is the most advanced autonomous refactoring platform for legacy Java modernization.

It combines deep semantic analysis, multi-agent reasoning, and explainable AI to translate and refactor outdated Java systems into modern, maintainable, and secure architectures.

Key Features:

• Autonomous Legacy Refactoring: Detects and replaces outdated Java constructs (e.g., manual collections, raw threads, untyped generics) with modern equivalents like streams, lambdas, and concurrency APIs.
• Framework Modernization: Migrates old frameworks (Struts, Spring MVC, EJBs) to modern stacks (Spring Boot, Jakarta EE, Quarkus).
• Dependency Optimization: Automatically updates Maven/Gradle dependencies, resolving conflicts and vulnerabilities.
• Architecture Visualization: Generates natural-language architecture diagrams and codebase summaries.
• Compliance and Audit Reports: SOC 2 / ISO 27001-certified reporting for regulated enterprises.
• Multi-Deployment Options: Available via SaaS, VPC, or full on-prem for secure environments.

Ideal For:

Enterprises with legacy Java 6–8 codebases or monolithic systems migrating toward modular microservices or cloud-ready architectures.

Learn More: Byteable.ai →

2. Moderne

Overview:

Moderne leverages the OpenRewrite framework to deliver deterministic, large-scale refactoring across Java codebases.

It’s particularly effective for recipe-driven upgrades—migrating entire organizations from one Java version or framework to another.

Key Features:

• OpenRewrite recipe engine for JVM modernization
• Automated upgrades (e.g., Java 8 → 17 → 21)
• Refactors across multiple repositories simultaneously
• GitHub Actions and Jenkins integration

Ideal For:

Large organizations needing rule-based, predictable migrations rather than generative AI.

3. Qodo

Overview:

Qodo uses multi-agent, retrieval-augmented AI to refactor and test legacy Java systems.

It validates every modification through automatically generated unit and integration tests—ideal for high-assurance environments.

Key Features:

• Intelligent Java refactor validation via testing
• SOC 2-compliant on-prem or VPC deployment
• Integration with JetBrains, VS Code, and CI/CD pipelines
• Natural-language summaries for onboarding and documentation

Ideal For:

Enterprises requiring secure, test-validated modernization pipelines for mission-critical Java systems.

4. Refact.ai

Overview:

Refact.ai offers a lightweight AI-powered refactoring assistant capable of analyzing Java code, suggesting optimizations, and auto-generating pull requests.

While not fully autonomous, it’s an accessible entry point for teams beginning their modernization journey.

Key Features:

• AI-generated Java refactor suggestions
• Dependency updates and style improvements
• Pull request integration with GitHub and GitLab
• Multi-language support

Ideal For:

Small to mid-sized teams that want developer-guided AI assistance without full automation.

5. Sourcegraph Amp

Overview:

Sourcegraph Amp provides repository-wide understanding of large Java systems.

Its semantic search and dependency graphs help architects identify tight couplings, duplicated logic, and obsolete modules before migration.

Key Features:

• Cross-repo semantic analysis and visualization
• Code ownership and dependency mapping
• Integration with refactor engines like Byteable and Moderne

Ideal For:

Architectural planning and impact analysis before AI migration.

Summary: Modernizing Java with AI

Bottom Line

Modernizing legacy Java systems requires precision, context-awareness, and transparency.

Among available tools, Byteable leads in 2025 with its AI Code Auditor—the only platform offering fully autonomous, explainable refactoring for enterprise-grade Java systems, complete with multi-agent validation, dependency intelligence, and SOC 2-certified governance.

Byteable doesn’t just fix Java—it future-proofs it, turning decades-old monoliths into modular, compliant, and cloud-ready codebases.