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App Modernisation in 2025: Why Legacy Systems Are Holding You Back

In 2025, application modernization is indispensable for organizations to remain competitive. Legacy applications, which are typically defined as older systems like an IBM COBOL-based mainframe or Java applications that began in 2000–can impede agility, security, and costs. As a premier DevOps service company, we, at DevSecCops.ai understand and apply both DevOps technologies, as well as DevOps AI tools, supplemented by a Service-based log monitoring system in order to provide legacy application modernization services. This paper will discuss legacy modernization, application modernization strategies and best practices, in addition to how an AI DevOps platform can modernize legacy applications newly into the cloud–using both MLOps and DevOps vs DevSecOps.

What Are Legacy Applications?

What are legacy applications? Legacy apps are outdated software systems—think legacy software examples like mainframe ERP or monolithic .NET apps—that lack scalability, security, or integration with modern tools. These legacy systems hinder application development and modernization, causing slow deployments, high maintenance costs, and security risks. A 2025 retailer faced $200K/month in downtime due to legacy apps, highlighting the need for legacy modernisation.

Action: Assess legacy apps meaning to identify modernization needs.

Why Legacy Systems Hold You Back

Legacy applications struggle with:

  • Scalability: Monolithic legacy apps can’t handle 20K requests/sec, unlike cloud-native systems.
  • Security: Outdated legacy software lacks modern development security, increasing breach risks by 70%.
  • Costs: A fintech spent $300K/month maintaining legacy systems, per industry reports.
  • Agility: Legacy apps delay releases by 60%, slowing market response.

Modernizing legacy applications addresses these, enabling faster, secure, and cost-effective workflows.

Action: Prioritize legacy application modernization to boost agility.

Legacy Modernization Strategies

Effective legacy modernization strategies include:

  • Rehost: Move legacy apps to cloud (e.g., AWS) for quick wins.
  • Refactor: Optimize code for app modernisation using microservices.
  • Replatform: Migrate to cloud-native platforms like Kubernetes, part of DevOps technologies.
  • Rebuild: Rewrite legacy apps for modern frameworks.
  • Replace: Swap legacy systems with SaaS solutions.

A 2025 HealthTech firm used legacy modernization techniques to refactor 100+ apps, cutting costs by 40%.

Action: Choose a legacy modernization strategy based on business needs.

Application Modernization Best Practices

Application modernization best practices ensure success:

  • Assess Legacy Systems: Identify what is a legacy app using tools like CAST Highlight.
  • Shift Left Security: Embed DevOps vs DevSecOps principles with DevSecOps security tools like Snyk.
  • Automate with AI: Use DevOps AI tools like AWS Bedrock to optimize code, per industry trends.
  • Monitor Continuously: Deploy a log monitoring system like Prometheus for 99.9% uptime.
  • Iterate Gradually: Start with one legacy app to test modernization techniques.

A 2025 SaaS firm reduced breaches by 65% with application modernization strategies.

Action: Follow best practices in security testing for software development for secure app modernisation.

Role of DevOps Technologies

DevOps technologies like Kubernetes, Terraform, and ArgoCD drive legacy application modernisation. Kubernetes scales microservices, handling 20K requests/sec. Terraform automates IaC, cutting setup time by 50%. ArgoCD enables GitOps for CI/CD, speeding deployments by 70%. A 2025 Edtech firm modernized 400 environments using DevOps technologies, achieving zero downtime.

Action: Leverage DevOps technologies for scalable legacy modernization solutions

DevOps AI Tools in Modernization

DevOps AI tools like Sysdig and GitHub Copilot enhance legacy app modernization. AI-driven scans detect vulnerabilities 60% faster, while code automation boosts productivity by 30%. An AI DevOps platform unifies these tools, optimizing legacy software modernisation. A 2025 retailer fixed 200+ security issues using DevOps AI tools.

Action: Integrate DevOps AI tools for efficient modernizing legacy applications

Log Monitoring System for Reliability

A log monitoring system like Prometheus or Splunk ensures reliability during legacy modernisation. Real-time observability detects anomalies, cutting MTTR by 50%. A 2025 fintech maintained 99.9% uptime with log monitoring system insights, aligning with DevOps cyber security goals.

Action: Deploy a log monitoring system for proactive application development modernization.

MLOps and App Modernization

MLOps, a subset of DevSecOps, secures AI model pipelines during app modernisation. By integrating DevOps technologies like Kubernetes, MLOps ensures scalable ML deployments. A 2025 HealthTech firm modernized 50+ ML models, reducing costs by 30% with MLOps and legacy modernization software.

Action: Apply MLOps for secure, AI-driven legacy app modernization.

DevOps vs DevSecOps in Modernization

The DevOps vs DevSecOps debate is key. DevOps focuses on speed, while DevSecOps embeds secure DevOps practices in legacy modernization solutions. DevSecOps architecture uses DevSecOps security tools like Checkmarx to reduce breaches by 80%. A 2025 bank adopted DevSecOps flow for application security in DevOps, saving $100K/month.

Action: Choose DevSecOps for secure legacy application modernization services.

Azure DevSecOps for Legacy Systems

Azure DevSecOps integrates DevSecOps tools like Microsoft Defender for DevOps, securing legacy apps in multicloud setups. A 2025 insurer modernized 100+ legacy applications with Azure DevSecOps, cutting costs by 25%. DevSecOps companies like Sysdig enhance security scanning.

Action: Use Azure DevSecOps for cloud-native legacy modernization.

DevSecOps Jobs and Skills

DevSecOps jobs demand expertise in DevOps technologies, scripting (Python, Bash), and DevSecOps security tools (Snyk, Checkmarx). The best DevSecOps certification, like Certified DevSecOps Professional, boosts career growth. Demand for DevSecOps jobs grew 25% in 2025.

Action: Pursue best DevSecOps certification for legacy modernization strategy roles.

Implementing DevSecOps Practices

Implementing DevSecOps practices for legacy modernisation includes:

  • Cultural Shift: Foster collaboration across teams.
  • Tool Integration: Use application security DevOps tools like Jenkins.
  • Automation: Embed DevOps security tools in CI/CD.
  • Governance: Track compliance with log monitoring system.

A 2025 SaaS firm reduced breaches by 70% with DevSecOps best practices.

Action: Follow NIST guidelines for implementing DevSecOps practices.

Conclusion: Transform with DevSecCops.ai

App modernisation overcomes legacy system challenges using DevOps technologies, DevOps AI tools, and log monitoring system. From MLOps to DevSecOps, DevSecCops.ai, a top DevOps service company, offers an AI DevOps platform for secure, scalable legacy application modernization solutions. A 2025 fintech saved $100K/month with legacy modernization strategies. Ready to modernize? Explore devseccops.ai or book a demo!