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What tools are used for application modernization?

Christin Wiedemann, PhD
Senior Director,
Slalom
Published:
8 minute read

TL;DR

  • If you’re thinking about tools before you name business outcomes, you’re introducing undue risk in your application modernization work. The most successful modernizations start with business goals like reducing technical debt, accelerating software delivery, improving resilience, strengthening security, and enabling AI adoption.
  • Tooling matters and changes frequently, but process matters more. Teams that focus on repeatable workflows, multi-tiered context architecture, and evidence-based decisions outperform those chasing the latest tools.
  • This post explains the tool ecosystem that supports those outcomes and how the categories work together to modernize applications at scale.

JUMP TO:

What categories of tools are used in modernization?

Several categories of tools work together in application modernization. Traditionally, organizations focused on cloud migration, DevOps, containers, and monitoring. Today, many modernization programs also include AI-powered analysis and automation tools that help teams understand and transform legacy applications more quickly.

Meanwhile, nearly two-thirds of IT leaders rank cost management as a top priority, making modernization outcomes more important than modernization activity, including focusing too narrowly on tools instead of strategies.


 14 Application modernization tool categories

1. Agentic workflow and orchestration

What it does

Coordinates AI agents across analysis, development, testing, and operational workflows

Why it matters

Accelerates software delivery and modernization program outcomes

Examples
  • LangGraph & LangSmith
  • Microsoft Copilot Studio
  • Microsoft Agent Framework
  • Amazon Bedrock: Agent Core
  • Google Agent Development Kit (ADK)

2. AI-assisted software engineering

What it does

Supports developers with code generation, code review, documentation, testing, and workflow automation  

Why it matters

Accelerates the software delivery life cycle (SDLC)

Examples
  • Claude Code
  • Cursor
  • GitHub Copilot
  • Kiro
  • Codex

3. AI-powered modernization

What it does

Uses AI to analyze legacy code, document business logic, identify dependencies, generate test cases, and accelerate activities

Why it matters

Improves speed, traceability, and confidence

Examples
  • Amazon Bedrock
  • OpenAI GPT-based modernization accelerators
  • Microsoft Foundry
  • Google Gemini Enterprise Agent Platform 

4. Assessment and discovery

What it does

Analyzes applications, dependencies, infrastructure, and technical debt

Why it matters

Exposes current-state complexity and prioritize what should be modernized, how

Examples
  • Azure Migrate
  • AWS Transform
  • CAST
  • GitHub Copilot Modernization Agent
  • Mechanical Orchard
  • Moderne

5. Change management and adoption

What it does

Helps manage workforce transition, skills development, communication, and adoption

Why it matters

Aligns people, not just process and tool improvements

Examples
  • Pendo
  • WalkMe
  • Whatfix

6. Cloud migration

What it does

Moves apps, workloads, databases, and infrastructure from on-premises environments to cloud platforms

Why it matters

Enables scalability, flexibility, and access to modern cloud services

Examples
  • AWS Application Migration Service
  • Azure Migrate
  • Google Cloud Migrate
  • Cloud Hound
  • CAST

7. Containerization and orchestration

What it does

Packages apps into portable containers and manages them across environments

Why it matters

Offers scalability, resilience, and cloud-native operations

Examples
  • Docker
  • Kubernetes
  • Red Hat 
  • OpenShift

8. Data modernization

What it does

Transforms legacy data environments into modern analytics and AI-ready platforms

Why it matters

Enables real-time insights and decision-making

Examples
  • Databricks
  • Microsoft Fabric
  • Snowflake

9. DevOps and automation

What it does

Automates software development, testing, deployment, and infrastructure management  

Why it matters

Improves delivery speed and consistency

Examples
  • GitHub Actions
  • GitLab CI/CD
  • Jenkins
  • Azure DevOps 

10. Infrastructure as code (IaC)

What it does

Automates infrastructure provisioning and management using code

Why it matters

Minimizes costly, risky manual configuration

Examples
  • AWS CloudFormation
  • Terraform
  • Pulumi
  • Bicep

11. Integration and API management

What it does

Connects modern apps with legacy systems, cloud services, databases, and external partners

Why it matters

Enables seamless connectivity across modern and legacy environments

Examples
  • Apigee
  • Boomi
  • MuleSoft

12. Logging and analytics

What it does

Collects, stores, searches, and analyzes operational and security data across apps and infrastructure

Why it matters

Provides the operational insights needed for troubleshooting, optimization, and security monitoring

Examples
  • Elastic (ELK Stack)
  • Grafana Loki
  • Splunk

13. Monitoring, APM, and observability

What it does

Gives visibility into app performance, infrastructure health, reliability, and user experience

Why it matters

Powers proactive issue identification and resolution

Examples
  • Datadog
  • Dynatrace
  • New Relic

14. Security and risk management

What it does

Helps secure modernized environments and meet compliance requirements

Why it matters

Reduces operational risk throughout modernization programs

Examples
  • Microsoft Defender for Cloud
  • Palo Alto Prisma Cloud
  • Wiz
  • SonarQube
  • Snyk
  • ChainGuard

How do cloud platforms support modernization?

Cloud platforms serve as the foundation for zero legacy and app modernization efforts because they provide scalability, flexibility, and access to advanced services such as AI, analytics, and automation.

The three leading platforms are:

  1. Amazon Web Services (AWS)
  2. Microsoft Azure
  3. Google Cloud Platform (GCP)

Many organizations also adopt hybrid and multi-cloud strategies to balance cost, security, compliance, and vendor flexibility. Modernization leaders increasingly evaluate cloud platforms based on how well they support future AI initiatives, not just current infrastructure needs.


In 2024, 60% of large enterprises repatriated at least one workload from public cloud. The broader shift toward hybrid modernization strategies that optimize for cost, resilience, and control rather than cloud adoption as a catch-all solution continue.


What are the top containerization and orchestration tools?

Containers have become a standard modernization pattern because they make applications easier to deploy, scale, and maintain.

The most widely used tools include:

  • Docker
  • Kubernetes
  • Red Hat OpenShift
  • Rancher

These technologies help organizations move away from tightly coupled legacy architectures toward more flexible cloud-native environments. The goal is not simply rehosting legacy software or capex reduction; it’salso to create platforms that can evolve as business needs change.


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THE SLALOM APPLICATION MODERNIZATION GUIDE

Legacy isn’t about age.

A 20-year-old system can be strategically valuable, and a two-year-old platform can create debt. Legacy needs to be addressed when it starts to limit your organization's ability to adapt, automate, integrate, secure, or innovate at the speed your business requires.

Get a practical approach to reducing technical debt, strengthening security, and building AI-ready application architectures that scale.


What DevOps tools are commonly used in application modernization?

Popular developer operations (DevOps) tools include GitHub Actions, GitLab CI/CD, Jenkins, and Azure DevOps, which support continuous integration/continuous delivery, automated testing, and release management. Terraform enables infrastructure as code, helping teams provision and manage cloud environments consistently, securely, and at scale.

Why are these tools prioritized?

DevOps tools help organizations automate the entire software delivery life cycle (SDLC)—from planning and building to testing, deployment, operations, and feedback. By automating the SDLC, teams can release new features faster, improve reliability, and reduce maintenance burdens (aka time, money, drudgery).  

Most organizations still get the most value from CI/CD automation, automated testing, IaC, security integration, and release reliability. AI engineering capabilities accelerate those practices rather than replace them. AI-assisted development capabilities, including test generation and execution, documentation support, and software engineering copilots pull three powerful levers. They:

  1. Accelerate delivery
  2. Improve developer productivity
  3. Help teams maintain quality and consistency

However, the tools are only as good as the strategy behind their use and the competence of your team has using them. Organizations achieve superior results when automation comes together with clear architectural standards, embedded security practices, and effective governance. You need a delivery model that aligns technology and talent investments to measurable business outcomes.


What monitoring, APM, and observability tools are needed?

Modern applications span cloud platforms, APIs, containers, databases, and microservices. To maintain performance and reliability across these distributed environments, organizations rely on monitoring, application performance monitoring (APM), and observability tools.


What’s the difference between monitoring, APM, and observability tools?

Monitoring tools are for detection, including detecting outages, performance degradation, and operational issues in real time. They ask, Is something wrong? An example outcome might be that "Response times are increasing and error rates are rising."

APM tools are for diagnosis. They help teams diagnose application bottlenecks and improve the speed and reliability of business-critical services. They ask, Why is the application slow or failing? An example outcome might be, "The payment API is causing transaction delays."

Observability tools are for root-cause analysis. They provide end-to-end visibility across applications, infrastructure, APIs, and dependencies to help teams truly, completely resolve complex issues. They ask, What is happening across the entire system and why? An example outcome might be, "A cloud networking change is affecting multiple services and creating downstream performance issues."



What do observability platforms help IT teams understand?

Modern observability platforms help teams answer questions across five areas critical areas:

  1. Application performance: Is the application responding quickly and reliably?
  2. Infrastructure health: Are servers, containers, databases, and cloud resources operating as expected?
  3. User experience: Are customers experiencing slowdowns, errors, or outages?
  4. Security events: Are security threats or configuration issues affecting system performance?
  5. System dependencies: Which APIs, services, databases, or integrations are causing bottlenecks?

Common monitoring, APM, and observability platforms

Datadog

Gives visibility into application performance, infrastructure health, cloud services, containers, logs, and distributed systems

Top questions it answers:

  1. Where is application performance degrading?
  2. Which infrastructure component is causing the issue?
  3. How is performance trending across environments and services?
Dynatrace

Gives visibility into end-to-end application performance, user experience, service dependencies, infrastructure, and AI-driven root cause analysis

Top questions it answers:

  1. What is the root cause of this performance issue?
  2. Which service dependency is creating the bottleneck?
  3. How is user experience affected?
New Relic

Gives visibility into application performance, user transactions, APIs, infrastructure, logs, and distributed traces

Top questions it answers:

  1. Which transactions are performing poorly?
  2. Where are users experiencing latency or errors?
  3. Which application changes impacted performance?
OpenTelemetry

Gives visibility into traces, metrics, and logs across applications, services, APIs, and infrastructure

Top questions it answers:

  1. How does a request move across systems and services?
  2. Where are latency and failure points occurring?
  3. Which dependencies are impacting application performance?
Splunk

Gives visibility into logs, events, operational data, security activity, and system telemetry

Top questions it answers:

  1. What happened before, during, and after the incident?
  2. Are there security or operational anomalies affecting performance?
  3. What patterns can help prevent future issues?

What integration and API management tools are important?

The strategy based on your modernization goals will always be more important than the tools.  

Most modernization programs connect new systems with existing applications and data sources. It’s rarely work that happens on a blank slate. This makes integration and API management one of the most critical—and often most underestimated—parts of modernization. It’s tricky to pull something entangled out and embed something new.

Typical modernization goals and integration solutions

If your goal is to modernize without rewriting everything, integration platforms and tool help expose legacy functionality through APIs instead of refactoring systems.

If your goal is to accelerate cloud migration, integration platforms and tool help connect cloud and on-premises applications during transition periods.

If your goal is to Improve customer experience, integration platforms and tool help enable real-time data sharing across channels and applications.

If your goal is to reduce technical debt, replace brittle point-to-point integrations with governed APIs.

If your goal is to enable AI and analytics, create consistent access to trusted enterprise data across systems.

If your goal is to improve security and compliance, centralize API governance, monitoring, and access controls.

But, in most enterprises, the goal isn’t one of these outcomes—it’s all of these outcomes. Tool and platform capabilities overlap, so it can be hard to suss out the tradeoffs. Keep in mind that the best platform is rarely the one with the most capabilities. The best platform is the one that best aligns with your modernization strategy, governance model, operating model, and long-term architecture vision.


Questions technology leaders should ask before selecting modernization tools

Avoid favoring the tool that has the longest feature list. Focus, instead, on uncovering the operational and architectural consequences related to each tool.

Questions about architecture and future readiness

  • Will this simplify our architecture or create more complexity (and indebt us down the road)?
  • Will this accelerate access to trusted enterprise data?
  • How resilient is this architecture as our business, vendors, and technology landscape change (even in ways we can’t imagine yet)?
  • How well does this scale (what breaks) as integrations, data, and business capabilities grow?

Questions about operational complexity

  • Which capabilities become simpler, and which become more complex?
  • What visibility will we gain? Lose?
  • What new operational burden are we taking on, and is that the right trade?
  • What skills does our team have, and how do we close gaps?

Questions about governance and ownership

  • Can we govern, secure, and manage this consistently across the enterprise?
  • How will we prevent API sprawl, dupes, and security risk?
  • Who owns this after implementation, and do we have the skills to operate it successfully?
  • How dependent will we become on this platform, its ecosystem, and its vendor or services?

Questions about business value

  • Where are we creating future lock-in (and adding long-term costs)?
  • How quickly can we prove business value?
  • How will we measure success today, tomorrow, and three years from now?
  • What is the cost of waiting vs. choosing not to modernize?

APPLICATION MODERNIZATION CONSULTING

Slalom’s application modernization services

Slalom helps organizations progress toward Zero Legacy with modernization initiatives focused on measurable business outcomes.

Our customers around the globe are modernizing mainframes, applications, and enterprise data with results that include:

  • 2–4x faster delivery for a U.S. education agency through AI-enabled engineering
  • $100MM projected savings and a 60% reduction in refactoring time for a global technology leader
  • 30% reduction in technical debt and $1.1MM reduction in annual mainframe operating costs for an iconic manufacturer and retailer
  • 66% lower compute costs and 50% faster workflows for a major federal healthcare agency
  • 5–9x engineering velocity increase using AI-accelerated modernization for a leading financial services provider

We partner with Amazon Web Services (AWS), Databricks, Google Cloud, Microsoft, Open AI, Salesforce, Snowflake, and over 700 of the world’s leading technology providers to support modernization across complex enterprise environments.




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