AI-powered legacy code modernization services

Modernize complex legacy systems faster, without stopping your business. AI reads, maps and rewrites old code, while our engineers make every final decision. Changes roll out in phases, with zero downtime.
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20+

years in IT

300+

engineers

94%

client retention

Abto Software is a Microsoft Solutions Partner with 20+ years in software development, 270+ clients across industries and a 4.9 rating on Clutch. Our in-house AI/R&D department has been building AI expertise for years, and modernization projects draw directly on it.

We combine AI-assisted code analysis with hands-on engineering to recover undocumented business logic, update aging architectures and move applications to modern, supported technologies. Our team regularly works with VB6, .NET Framework and monolithic systems.

Modernize your code. Keep your business running. Get a free assessment

AI-driven legacy modernization services

Legacy modernization is slow when every line of undocumented code has to be analyzed manually. We apply AI to speed up that work, while our engineers check the results and make every final decision.

Code assessment and mapping

AI maps dependencies, finds dead code and identifies business rules, so you see the full picture before you commit a budget.

Business logic recovery

We extract the rules hidden in undocumented code and turn them into specs your team can read and review.

AI-assisted code migration

We migrate VB6, VBA and .NET Framework code to modern C# and .NET, and our engineers review every change before it’s merged.

Monolith to modular architecture

We add service layers around your monolith, so you can replace it piece by piece instead of rewriting everything at once.

Test generation and regression safety

AI generates characterization tests that capture how your system behaves today, so every change is checked against it.

UI and front-end modernization

We move desktop and legacy web interfaces to React, Angular or Blazor without changing the workflows users rely on.

Cloud migration and data consolidation

We merge siloed databases and move workloads to Azure, AWS or Google Cloud Platform in phases, so operations keep running.

AI readiness and integration

We expose legacy functions and data through APIs, so your AI tools can use them without a full rebuild.

Choose the right path for your legacy system

There’s no one-size-fits-all approach to AI legacy system modernization, so we often combine multiple strategies within one system.

ApproachWhat it meansBest when
RehostMove the existing application to new infrastructure with little or no code changes.Your application works well, but the infrastructure is outdated, expensive, or difficult to maintain. 
ReplatformMove the application to a supported runtime, platform, or cloud service while keeping its core architecture. The current platform is outdated but the architecture still fits your business.
Refactor and convertImprove code structure or convert legacy code, such as VB6 to C#, while preserving existing functionality. Your business logic is valuable but outdated languages, dependencies, or poor code quality make maintenance difficult. 
Incremental re-architectureGradually replace legacy components or modules while keeping the rest of the system running. You need to modernize a business-critical application without taking the entire system offline. 
RebuildDevelop a new application using modern technologies, architecture, and design while preserving essential business logic and functionality. The existing system is too outdated or complex to modernize cost-effectively, and targeted improvements are no longer practical. 
API wrapping Add APIs to connect legacy functionality and data with modern applications, cloud services, or AI solutions. Your core software system works but you need new integrations, automation, or AI capabilities.

Legacy modernization with AI, led by engineers

We modernize outdated systems by putting generative AI and AI agents to handle the analysis and routine code work that used to take weeks. Our architects decide where the system should go, review every change and sign off before anything reaches production.

AI does the heavy lifting. We decide what ships. Test it on your code
1
Understand
AI helps teams understand legacy code in days and uncovers the logic nobody documented.
2
Analyze and convert
AI analyzes and transforms your code one module at a time, even in large legacy software systems.
3
Protect behavior
Generated tests capture how your system works today, so every change is checked against it.
4
Automate the repetitive work
AI agents accelerate dependency mapping, documentation and test generation.
5
Govern every change
Everything runs within your security policies, with engineer review and a full audit trail.

Legacy technologies we work with

  • Visual Basic 6 (VB6)
  • VBA
  • Windows Forms
  • ActiveX controls
  • ADODB
  • .NET Framework
  • LISP
  • MATLAB-dependent modules
  • AutoCAD-dependent modules
  • Manifest V2 browser extensions
  • Static HTML front ends

Tech stack

  • Backend

    .NET 6/7+, ASP.NET, ASP.NET Web API, C#, C++, Python, Node.js, PHP, GraphQL, REST

  • Frontend

    React, Angular, Vue, Blazor, WPF, JavaScript

  • Infrastructure

    Azure, AWS, Google Cloud Platform, DigitalOcean, Docker, Kubernetes, Terraform, Jenkins, Keycloak, RabbitMQ

  • Database

    MS SQL Server, MySQL, PostgreSQL, MongoDB, Redis, Elasticsearch

  • Standards & compliance

    HIPAA, GDPR, HITECH, HL7, FHIR, CDA, DICOM, NCPDP

  • AI and modernization tools

    OpenAI, LangChain, LangGraph, PyTorch, TensorFlow, Keras, scikit-learn, OpenCV

illustration

    Case studies

    RPA platform legacy modernization

    RPA platform legacy modernization

    Industry: Information technology

    Monolithic RPA platform → plugin-based architecture on .NET 7, Kubernetes and Manifest V3

    Fragile automations caused about 80% of bugs, and enterprise customers had to fully uninstall and reinstall to upgrade. We built a plugin architecture around the monolith and a new installer with partial upgrades, keeping existing automations backward compatible. The engagement has been ongoing since 2019.

    The results we achieved:

    • Upgrades in days instead of up to a month
    • 80% fewer automation errors
    • Browser extensions migrated to Manifest V3 within six months
    • Citrix and Terminal Server support with automatic session relaunch
    RPA platform legacy modernization
    Belt-drive system engineering toolkit

    Belt-drive system engineering toolkit

    Industry: Machinery & manufacturing

    VB6, VBA and LISP → C# on .NET 6/7 with WPF, Blazor and Xamarin

    The toolkit ran on an unsupported VB6 framework that suffered from data corruption and crashes, while dependencies on MATLAB and AutoCAD kept licensing costs rising. We migrated the code to .NET, rebuilt engineering algorithms with precision checks to prevent regressions, recreated MATLAB- and AutoCAD-dependent functionality to reduce third-party dependencies, and moved shared business logic into common libraries.

    The results we achieved:

    • 75% of users pay lower licensing costs
    • Six design modules consolidated into one toolkit
    • Fewer crashes and lower maintenance burden
    • Faster training through unified workflows

    Custom CRM upgrade for an international charity

    Custom CRM upgrade for an international charity

    Industry: Nonprofit

    VB6 desktop CRM with 14 used across 14 offices → C# .NET web app with React and REST APIs

    The organization’s staff relied on slow VPN and Remote Desktop sessions, and offices exchanged data through insecure file exports. We migrated the legacy CRM to .NET in iterative steps, with manual and automated testing at each stage, so every office stayed fully operational during the transition.

    The results we achieved:

    • Zero manual work to keep systems synchronized
    • Faster, secure HTTPS access instead of VPN plus Remote Desktop
    • Responsive interface that works on mobile devices
    Custom CRM upgrade for an international charity
    VB6 to C# conversion for Swiss social authorities

    VB6 to C# conversion for Swiss social authorities

    Industry: Government

    VB6 Windows Forms with ActiveX and ADODB → C#/.NET three-tier application with ADO.NET

    The children sponsorship system ran on VB6 with obsolete ActiveX controls and raw data access code. We reverse-engineered the application, converted it to C# and refactored it into a clean three-tier architecture, separating business logic from data access.

    The results we achieved:

    • Lower license and support exposure for 75% of users
    • Runs on 64-bit platforms with no brittle plugins
    • Documented code and knowledge transfer to the client team

    Clutch: 4.9 / 5

    “We wanted to move our existing VB6 Project to a web-based ERP system and integrate our mobile app. The entire process needed to be completed without causing issues to the existing system. Abto worked closely with us to ensure a smooth integration with the existing system and no downtime for existing clients during the migration.”

    Read the full review

    NDA
    Project Manager, Software Development Company

    Our AI code modernization framework

    1
    Assess
    We start with AI-powered legacy system analysis to map dependencies, risks and the rules that matter to your business.
    2
    Plan
    We choose the modernization approach for each module and give you a roadmap with costs, milestones and rollback points.
    3
    Prove
    One module goes first as a pilot. We compare the results with the old system before scaling up.
    4
    Modernize
    We convert and restructure code step by step: AI drafts the changes, and engineers review each of them.
    5
    Validate
    Regression tests and parallel runs confirm the new system works as intended, keeping the behavior your business depends on.
    6
    Evolve
    We support the new system, transfer knowledge to your teams and help you add new features.

    Modernizing systems that run your business

    Healthcare

    EHR, EMR, PACS, LIS, RIS, HL7 and FHIR interface engines, EEG and diagnostic device software, patient portals, telemedicine platforms

    Manufacturing & machinery

    ERP, MES, engineering design and calculation tools, CAD-integrated applications, PLM, quality management systems, industrial RPA and robotics integrations

    Fintech & financial services

    Core banking modules, payment processing, decision and risk models, customer support automation, KYC and AML workflows, reporting engines

    Logistics & supply chain

    WMS, TMS, package and delivery management platforms, fleet tracking, EDI integrations, order management systems

    Government & public sector

    Case management systems, benefits and sponsorship administration, document management, citizen portals, records and archive systems

    Nonprofit

    Custom CRM, donor and sponsor management, program and grant tracking, multi-office data synchronization, field reporting tools

    Start where you are

    1
    Modernization assessment
    A fixed-scope, AI-assisted review of your legacy codebases, architectures and risks.

    You get: a roadmap that shows what to modernize first, based on value, cost and risk.
    2
    Pilot project
    One bounded module modernized end-to-end and compared to the original system.

    You get: working proof on your own code, with real numbers on speed, quality and cost before full rollout.
    3
    Dedicated modernization team
    A team of engineers and architects who work on your modernization initiatives and support the system afterward.

    You get: predictable delivery, a team that knows your product inside out and capacity that grows with your roadmap.

    FAQ

    The timeline for AI-driven modernization depends on the system. The main factors are:

    • How much code there is and how tightly its parts are connected
    • Whether business rules are written down or exist only in the code
    • Whether older or less common technologies, like VB6 with ActiveX controls, are
    • involved
    • How many systems, databases and third-party tools it connects to
    • What architecture the modernized system should have
    • How much data needs to move

    AI speeds up the stages that traditionally take the most manual effort: code analysis, dependency mapping, recovering undocumented business rules, drafting code conversions, generating tests and writing documentation. Modernization strategies, architecture decisions, code review and final approval stay with our engineers, so speed never comes at the cost of control.

    The most reliable way to get a realistic estimate is an assessment or a pilot on one module, which shows how fast the chosen approach to legacy system modernization works on your own code.

    AI tools analyze, document, convert and test legacy code, while engineers set the direction and approve every change. The process usually includes six steps:

    • Assess the codebase and recover business rules
    • Plan an approach for each module, from rehost to rebuild
    • Prove the approach on a pilot module
    • Modernize in increments with engineer-reviewed AI output
    • Validate with generated regression tests and parallel runs
    • Support and evolve the new system

    Each step is described in detail in our AI code modernization framework.

    AI works best when it speeds up a well-structured engineering process, with experienced engineers guiding the work. Key practices include:

    • Capture current behavior in tests before converting any code
    • Keep humans in review for every AI-generated change
    • Modernize incrementally behind stable interfaces instead of in a single cutover
    • Turn recovered business rules into documentation your team owns
    • Measure the pilot against the old system before scaling
    • Keep your code and data inside approved, access-controlled environments

    We follow these practices on every modernization project and can explain to you how they apply to your system.

    The main benefit is speed without losing the business logic built into your legacy system.

    • Faster discovery: AI maps dependencies and business rules across large codebases in a fraction of the time manual analysis takes
    • Recovered knowledge: undocumented logic becomes readable specs your team can review
    • Lower risk: generated tests check every change against how the system works today
    • Faster delivery: generative AI drafts conversions and routine code, so engineers spend their time on design and review

    The risks are real, and each one has a specific control.

    • Lost business logic: managed with rule extraction and characterization tests
    • Incorrect AI output: managed with engineer review, CI checks and regression suites
    • Downtime: managed with incremental cutovers, parallel runs and planned rollbacks
    • Data and IP exposure: managed by running AI in approved, access-controlled environments
    • Compliance gaps: managed by designing for HIPAA, GDPR and HL7/FHIR from the start where they apply

    A top legacy modernization company proves its method on your code before it asks for a long commitment. When comparing partners:

    • Look for case studies on complex legacy software modernization with measurable results
    • Ask how AI helps the work and where engineers stay in control
    • Check if the partner adapts legacy modernization solutions to your system instead of pushing one approach
    • Make sure the end result is documented, testable software your team can maintain

    Our legacy application modernization services start with an assessment, so you can judge our work on your own code.

    Contact us

    Tell your idea, request a quote or ask us a question
    We take ownership to make it a success — because we build what we’re proud of.
    Yuriy Kapkovskyy linkedin
    Chief Sales and Marketing Officer, Co-owner