The 7 Best Legacy Modernization Tools For Digital Transformation

Quick summary 

This article explores seven top tools for legacy system modernization, highlighting features like AI-powered insight, automated documentation, and secure hybrid deployment. It compares Kodesage, AWS Migration Hub, MS Azure Migrate, and four others to help teams modernize legacy applications and manage complex systems at scale.

Are you considering modernizing your legacy systems?  

Pragmatic Coders reports that more than 70% of enterprises are still running legacy code, and for good reason. These systems work, but updating them can feel impossible without the right tooling. 

Thankfully, today’s modernization solutions include more than replatforming options. You’ll find LLM-powered code analysis, visual dependency mapping, secure deployment paths, and other key modernization features intended for all industries.

In this Kodesage article, we’re spotlighting seven top legacy modernization tools you should consider. If you’re looking to modernize safely, incrementally, and without losing institutional knowledge, start with the tools on this list.

But first…

What are legacy modernization tools?

Legacy modernization tools are platforms that help organizations update aging software systems without rewriting everything from scratch. These tools handle everything from cloud migration and code refactoring to API generation and database restructuring, all while keeping critical systems running.

Instead of manually rewriting millions of lines of COBOL or trying to replace fragile mainframe apps overnight, these tools automate much of the heavy lifting. Depending on the approach, they fall into one or more of these categories:

• Code analysis and refactoring tools that help teams understand, clean up, and restructure monolithic code
• Cloud migration tools that rehost or replatform legacy systems with minimal changes
• API integration platforms that expose legacy functionality to new apps and services
• Automated documentation and visualization engines that map dependencies and system behavior

The best tools go beyond raw automation. They surface system context, help teams prioritize effort, and reduce complexity with visual insights. They also support hybrid strategies. That means you can modernize piece by piece, preserving business continuity while reducing legacy debt.

Why are legacy modernization tools important? 

Here’s why the right legacy modernization tools make all the difference:

• Improved scalability: Move from rigid, monolithic systems to architectures that scale horizontally and vertically as demand grows.
• Cost efficiency: Cut maintenance overhead by automating routine tasks and optimizing how systems use infrastructure.
• Enhanced security: Apply security patches automatically, enforce up-to-date protocols, and meet modern cybersecurity standards.
• Faster time to market: Modular setups and automated deployments make it easier to ship new features without long delays.
• Phased modernization: From knowledge graphs to visual mapping, these legacy modernization solutions support secure, phased transformation.
• Better integration: Modernize with cloud support, API access, and third-party compatibility without rewriting your whole stack.

Best legacy modernization tools summarized

Here’s a quick comparison of the top tools featured in this review before we dive into the details:

Top 7 legacy modernization tools you should consider

1. Kodesage 

Kodesage is a AI-powered legacy knowledge platform built for teams who need to maintain or modernize complex legacy systems. They are built for secure on-premise and air-gapped deployments, helping enterprises to preserve legacy system knowledge, and eliminate the reliance on key personnel or external vendors.

Unlike tools that only help you migrate, Kodesage helps you understand what you already have by turning code, issue tickets, databases and documentation into a living, searchable knowledge base. This knowledge base extracts business logic from the connected sources, and standardizes this knowledge to make it easily accessible organization wide.

With Ask Kodesage, engineers, product managers, business analysts, QAs and support engineers can query systems in natural language and get accurate, real-time answers. The platform also auto-generates documentation, maps dependencies visually, generates unit or regression tests, and integrates with issue ticketing systems like Jira to suggest fixes for open issue tickets.

Whether you're dealing with COBOL, PowerBuilder, or Oracle Forms, Kodesage gives you the visibility and control you need to modernize safely.

Key features

• Natural-language querying: Ask Kodesage questions about your system and get instant, explainable answers. Generate unit or regression tests, assess feasibility of new features, and enable product managers to create discovery briefs independently.
• Docs studio: Generates and updates documentation as the code evolves, offering a template library that is fully customizable ensuring audit-ready documents.
• Visual dependency mapping: Creates interactive diagrams that show how systems connect across files, functions, and services.
• Issue analysis: Syncs with tools like Jira and Redmine to surface related code and automatically generates fix recommendations with detailed implementations guides.
• Secure deployment options: Supports on-premise and air-gapped installs for data-sensitive teams, while also offering VPC options on Azure and AWS.

Pricing

Unlike LLM based developer tools who often price based on tokens, Kodesage prices based on the number of systems connected. One system can have multiple data sources. There are no limits on feature usage neither on the number or complexity of questions.

Pros

• Connects to the entire codebase, providing strong context to LLMs
• Has legacy language specific parsers, and integrates multiple sources natively
• Supports secure, on-premise, and air-gapped environments
• Accelerates developer onboarding with real-time system Q&A and automates the majority of technical documentation
• It is not just a developer tool, and supports other teams like product, QA, and support
• Helps teams modernize without disrupting existing systems

Cons

• Built for enterprises and larger teams, no free version available

2. AWS Migration Hub

AWS Migration Hub offers a unified console to track and manage migration workflows across AWS services and supported partner tools. From discovery to modernization, it provides step-by-step guidance using journey templates for rehosting, replatforming, or refactoring. 

The platform collects real-time migration status, helping teams coordinate complex legacy transitions across regions and environments. It works well for organizations committed to AWS but has limited support for air-gapped or hybrid systems.

Key features

• Migration journey templates: Guided workflows for rehosting, replatforming, and refactoring applications.
• Asset discovery and grouping: Import or use agents to identify and organize on-prem systems.
• Visual dependency mapping: Generates application maps to uncover network-level connections.
• Automated strategy planning: Recommends migration paths based on resource analysis.
• Workflow orchestration: Automates moves for SAP, .NET, Java, and database systems.

Pricing

Migration Hub’s core planning and tracking tools are free. You only pay for the AWS services consumed during migration (like EC2 or Database Migration Service). 

Refactor Spaces is billed at $0.028 per environment hour and $0.000002 per API call, with a 90-day free period and ample free tier credits.

Pros

• View all your AWS tools in one unified dashboard.
• Use predefined templates to speed up planning.
• See hidden dependencies with visual maps.
• Get optimal path suggestions with the strategy builder.
• Refactor Spaces makes it easy to support microservices.

Cons

• Setup requires configuration expertise
• Does not automate the migration process itself
• Cost escalations are possible with poor resource planning

3. IBM Application Modernization Platform

IBM’s platform helps large enterprises modernize legacy systems built on mainframes like z/OS, COBOL, and CICS. It integrates AI-powered tools and cloud connectors to support rehosting, refactoring, and hybrid deployment. 

Financial services, government, and telecoms use it to preserve uptime while gradually modernizing core infrastructure. Designed for high availability, it blends legacy stability with newer analytics and security features, making it a trusted option for risk-sensitive modernization at scale.

Key features 

• Hybrid migration support: Enables step-by-step modernization by bridging mainframe systems with cloud platforms, reducing risk during transition.
• Uptime-first stability: Handles high-volume transactions reliably, ensuring mission-critical systems remain operational without disruption.
• AI analytics on mainframes: Applies machine learning to detect anomalies, tag sensitive data, and guide secure refactoring decisions.
• Mono2Micro refactoring: Automatically analyzes application behavior to convert monolithic codebases into microservices for improved agility.
• Quantum-safe encryption: Implements forward-looking cryptographic standards with built-in tools for meeting industry and regulatory compliance across environments.

Pricing

IBM does not publish pricing. Final costs depend on factors like workload complexity, AI usage, and hybrid deployment scale. Contact IBM for a custom quote aligned to z/OS scope and modernization goals.

Pros

• Delivers uptime under intense workloads
• Enterprise-grade support and SLAs
• Built for critical COBOL and CICS stability
• AI-enhanced data visibility for compliance
• Performance exceeds many cloud-native setups

Cons

• Expensive for smaller teams or light workloads
• Integration outside the IBM ecosystem is limited
• Requires extensive learning to fully maximize performance

4. Microsoft Azure Migrate

Azure Migrate is Microsoft’s unified hub for managing on-premises to cloud migration. It scans servers, workloads, and databases, evaluates readiness, and groups assets for streamlined execution. 

Whether teams choose rehosting, replatforming, or full refactoring, the platform offers built-in compatibility checks and seamless Azure service integration. Its dashboards provide a real-time view of progress, helping teams avoid missteps and optimize cloud costs through informed migration planning. 

Key features

• Asset discovery and grouping: Automatically detects virtual machines across Hyper‑V, VMware, and bare metal hosts.
• Compatibility assessment: Flags OS, app, and database readiness for Azure VM or platform services.
• Visual dependency mapping: Highlights app-to-app and server dependencies using drag-and-zoom diagrams.
• Migration guidance: Offers structured templates for common scenarios like SQL rehost or web app refactor.
• Application readiness checks: Integrates with Visual Studio and CLI tools to analyze Java and .NET readiness.

Pricing

Azure Migrate’s core tools, including discovery, assessment, dependency mapping, and planning, are free. Users pay only for Azure resources consumed during or after migration, such as virtual machines or managed databases. 

Code assessments via Azure SDK or Visual Studio tools are also free; additional Azure-native service use incurs standard platform charges.

Pros

• Centralized dashboard streamlines entire migration project tracking
• Automated asset grouping improves planning confidence
• Built-in dependency maps reveal unseen cross-service links
• Templates accelerate migration sequencing and execution
• Accurate VM right-sizing reduces over-provisioning risk

Cons

• Setup can be complex and time-consuming
• Some users report false-positive dependency visuals
• Limited real‑time migration tracking feedback reported

5. CAST Highlight & Imaging

CAST Highlight and Imaging work together as a software intelligence suite designed for high-speed legacy modernization planning. 

Highlight scans and assess application portfolios to uncover technical debt, cloud blockers, and open-source risks. Imaging then visualizes software architecture across code, data, and transaction flows.

By translating complex legacy systems into clear, interactive maps, CAST equips enterprise architects and developers with continuous visibility and faster decision-making throughout the modernization journey. 

Key features 

• Portfolio analysis: Assess cloud readiness, technical debt, and open-source risks across multiple apps.
• Architecture reverse-engineering: Auto-map databases, code layers, and transaction flows into interactive visuals.
• Modernization recommendations: Get AI-driven advice to rehost, refactor, rebuild, or retire systems.
• Cloud migration insights: Detect blockers, boosters, and inefficiencies before moving to the cloud.
• Enterprise scalability: Handle large portfolios with thousands of components.

Pricing

CAST pricing varies by code volume and deployment model. On-prem deployments follow a custom pricing model. Enterprise quotes are available for portfolio-wide assessments.

Pros 

• Fast portfolio diagnostics accelerate early decision making
• Detailed architecture maps aid refactoring planning
• Strategy advisor recommends modernization path precisely
• Cloud-ready insights reduce blocker removal effort
• Continuous tracking supports a long-term modernization lifecycle

Cons

• Initial scan requires full access to the codebase
• Visual reports may overwhelm non-technical stakeholders
• Performance dips reported on large application portfolios

6. Google Cloud Dual Run

Google Cloud Dual Run enables organizations to validate legacy mainframe migrations by running workloads on both mainframe and Google Cloud simultaneously. This parallel execution allows real-time comparison of outputs, ensuring functional and performance parity before switching to the cloud. 

It supports batch jobs and live transactions, making it ideal for high-assurance transitions. Dual Run ensures that modernization can happen with zero disruption, as teams test thoroughly before promoting cloud environments to production.

Key features  

• Parallel execution: Runs workloads on mainframe and cloud simultaneously to compare real production behavior.
• Equivalence dashboards: Visual dashboards highlight discrepancies in real time, supporting risk-free validation.
• Two-phase validation: Retain mainframe as primary until parity is verified, then promote cloud.
• Integration suite: Works with Google’s Mainframe Assessment Tool and Connector to ease planning.
• Batch and transaction support: Handles both scheduled and real-time jobs for full coverage.

Pricing

Google Cloud does not publish standalone pricing for Dual Run. Pricing depends on licensing, support, and required integrations. Contact Google Cloud sales for a tailored quote and infrastructure cost estimation.

Pros

• Parallel validation minimizes migration rollback risk
• Built-in dashboards show real-time workload parity
• Supports both batch and transactional validation
• No disruption to current production systems
• Backed by Google’s high-speed global cloud infra

Cons

• Billing dashboard lacks transparency for some users
• Advanced setup needs experienced IT configuration
• Limited third-party user reviews are currently available

7. Mobilize.Net (GAP Velocity AI)

The last legacy modernization software on the list is Mobilize.Net’s GAP Velocity AI. This platform is designed to automate enterprise-scale migration of Windows and desktop applications, using hybrid deterministic and generative AI without requiring full rewrites. 

It scans VB6, PowerBuilder, Clarion, VB.NET, WinForms, and Access codebases to preserve business logic, naming conventions, and layered architecture. This leaves you with clean, compiled projects ready for testing and deployment, requiring minimal post-conversion remediation.

Key features

• Analyze legacy logic: Scans VB6, PowerBuilder, Clarion, VB.NET, WinForms, and Access code to map dependencies, control flow, and business rules. 
• Automated code conversion: Transforms 95–99% of legacy code into modern C#, .NET Core, Blazor, or web frameworks, minimizing manual rewriting and leveraging AI-driven templates to maintain consistency.
• Structure and logic preservation: Maintains naming conventions, project organization, application layers, and workflows to ensure fidelity and simplify maintenance and enhancements.
• Performance optimization: Generates optimized .NET assemblies that run as fast or faster than the original applications through automated refactoring and tuning.
• Cloud-Native Ready: Converts desktop and legacy apps into cloud-native architectures, adding support for Blazor, microservices, Azure-ready patterns, and more, to ensure modern scalability and extensibility

Pricing

Pricing is customized based on codebase size, complexity, and supported languages. Enterprise quotes are available upon request; exact pricing varies widely by project scope.

Pros

• Deterministic AI delivers consistent, high-quality code
• Scales to enterprise codebases exceeding millions of lines
• Backed by Mobilize.Net’s expert services for architecture and tuning
• Continuously updated for the latest .NET, Blazor, and security patches
• Supports the full modernization process, including documentation and testing.

Cons 

• Limited to Microsoft-centric legacy stacks (no Delphi or Oracle Forms support)
• Focuses on copying old functions rather than redesigning or adding new features
• Few publicly available independent user reviews

Best practices for legacy modernization 

Modernizing legacy systems requires careful planning and execution. These seven best practices help reduce risk and maximize long-term value:

• Conduct a comprehensive portfolio assessment: Evaluate system architecture, tech debt, and business value to define modernization priorities and avoid missteps.
• Prioritize high-impact applications: Focus on systems with strong business value and high risk first, rather than attempting full rewrites across the board.
• Define a modernization path using the 7-R framework: Choose the right strategy: rehost, replatform, refactor, rearchitect, rebuild, or retain for each system based on complexity and long-term needs.
• Use incremental modernization patterns: Apply models like the strangler fig or self-contained services to modernize in stages without disrupting active workloads.
• Map logic and dependencies visually: Reverse-engineer code and workflows to surface hidden risks and reduce migration surprises.
• Embed security and compliance early: Extract business rules and apply encryption, auditing, and access controls from the start.
• Adopt CI/CD and modular architecture: Enable iterative deployment and testing during modernization, reducing downtime and rollback risk.
• Engage stakeholders continuously: Communicate benefits clearly, manage expectations, and provide training to encourage buy-in and adoption.

Modernize legacy systems using Kodesage

Modernizing legacy systems is not one-size-fits-all. From cloud migration hubs to AI-powered code analyzers, this list highlights practical tools built for real enterprise needs. If your systems are running on old legacy tech stacks, and your company needs AI-based solutions to run on-premise, Kodesage is the right solution for you.

Kodesage helps you understand legacy code before you modernize. It transforms system data into a searchable knowledge base preserving business critical knowledge for the future. Kodesage generates living documentation, and maps dependencies, so your team can move with context, not guesswork. Going beyond AI developer tools, it empowers all teams involved in the software development lifecycle, helping your organization not only in modernization projects, but also planning phases and production support.

Book a custom demo to explore how Kodesage can support your legacy modernization project.