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From Old to Bold: A Strategic Guide to Legacy System Integration

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For many enterprises, an efficient legacy system integration can be a big challenge.

And if you’re one of them, this blog is specifically curated for you.

We’ve covered everything related to it – from the hurdles you might face to steps you need to take and how we can lend a hand in integrating those legacy systems seamlessly.

So, let’s get started!

Key Challenges of Legacy System Integration that You Might Face

Integrating legacy systems into modern IT environments can present various challenges due to the differences in technology, architecture, and data formats.

Here are some common challenges associated with legacy system integration:

1. Outdated Technology

Legacy systems often use outdated technologies, programming languages, and frameworks.

This can lead to difficulties in integrating as they may not be compatible with modern technologies.

2. Data Format and Structure

Your legacy system speaks an ancient data that’s totally different from what new systems use.

In short, their data structures are incompatible with modern standards.

Converting and mapping that data can be complex and may require significant effort.

3. Lack of APIs

Legacy systems might not have well-defined APIs or might lack APIs altogether.

This makes it challenging to make seamless communication between the legacy system and other applications or services.

4. Scalability Issues

Legacy systems may not be designed to scale efficiently to meet growing data or user demands.

Hence, integrating them into a modern, scalable infrastructure may require additional optimizations and upgrades.

5. Testing and Validation

Testing a legacy system is a bit like exploring a haunted house – you never know what spooky bugs might pop up.

Limited testing tools and the complexity of legacy code make testing more challenging.

👉 Explore Our Exclusive Software QA Services

How to Overcome Challenges While Integrating Legacy Systems? [Expert-Made Strategies]

For a better understanding, let’s divide strategies to overcome legacy system integration challenges.

Non-technical Strategies

  • Conduct a thorough assessment of the existing legacy systems to understand their architecture, data structures, and dependencies.
  • Determine what specific benefits the organization aims to achieve through integration.
  • Prioritize integration steps based on business criticality (from low-risk to complex one).
  • Utilize middleware and integration tools to facilitate data transfer, protocol conversion, and communication between different technologies.
  • Develop a clear strategy for data mapping and transformation.
  • Develop APIs for legacy systems where possible.
  • Implement robust security measures to protect both legacy and modern systems.
  • Implement thorough testing at each integration phase.
  • Ensure that the architecture can handle future growth and increased demands on the system.
  • Keep both legacy and modern systems up to date with regular updates and patches.

Technical Strategies

  • Implement a service-oriented architecture to modularize legacy systems.
  • Use middleware solutions ESB or iPaaS to streamline communication between legacy and modern systems.
  • Develop APIs for legacy systems using tools such as Postman, Swagger, RAML, Insomnia, etc.
  • Use API management tools such as Apigee, AWS API Gateway, or IBM API Connect to control access, monitor usage, and ensure security.
  • Employ data integration tools and ETL processes to manage data migration and transformation. (Tools like Apache NiFi, Talend, or Informatica can assist in this process.)
  • Containerize legacy applications using technologies like Docker or Kubernetes.
  • Implement event-driven architecture to enable asynchronous communication between systems.
  • Consider code modernization techniques, such as rewriting or refactoring critical components of the legacy system to make them compatible with modern technologies.
  • Implement robust logging mechanisms and monitoring tools (e.g., ELK stack or Prometheus) to track the performance and behavior of integrated systems.
  • Adopt DevOps practices to streamline development, testing, and deployment processes.

👉 Check Out Our Insightful Blog on Azure DevOps vs. AWS DevOps

How to Integrate Legacy Systems with Modern Software Products? Top Methods

There are 4 main approaches when it comes to integrating legacy systems or applications.

Simply put, P2P integration is a way to connect two apps using custom code.

It’s the most common approach.

However, maintaining and scaling P2P connections is more complex and difficult to manage when the number of systems increases.

ESB is a middleware software architecture that provides a centralized, scalable, and flexible platform to integrate multiple systems.

It simplifies legacy system integration by providing a common communication bus and transformation services.

Mulesoft, Apache ServiceMix, and IBM Integration Bus (IIB) are a few examples of ESB tools.

Though an ESB seems better than P2P integration, however, it has significant limitations.

For example, it lacks load balancing and message call limits. Hence, crashes are frequent in busy environments.

What’s more, it isn’t well-suitable when it comes to microservices architecture.

API is a collection of rules, defining how an app should “respond” to access data or features of the other app.

It acts like a messenger, ensuring apps or systems communicate efficiently.

Currently, it’s the most common method to connect technologies or applications with one another.

But why?

  • Effortless integration of hundreds of apps
  • Compatible with cloud and microservices
  • Reusable API design
  • Optimize functionality with API gateways
  • Monetize opportunities

In case your legacy system was developed before APIs, first, you have to make it API-friendly.

But it’ll require fortune, experience, and even refactoring your legacy system.

However, the result will be worth the effort as API offers benefits that neither P2P integration nor ESBs have.

iPaaS is a cloud-based integration platform that streamlines the development, execution, and management of integrations between different systems.

It offers an array of pre-configured adaptors, connectors, APIs, and even ESBs.

In fact, “The global IPaaS market reached $6.68 billion, projected to hit $61.67 billion by 2030 with a 32.47% CAGR.” (Source)

But why it’s so popular?

  • Integration in a couple of hours
  • No need to bother with the maintenance
  • It can work with legacy programming languages and data formats like X12, EDIFACT, or COBOL.
  • It takes care of your compliance needs.
  • Support both over the cloud and on-premises

How do We Perform Legacy System Integration as a Software Product Engineering Company?

At Azilen, we take a holistic approach to legacy system integration.

Our team of integration experts understands the intricacies of legacy systems and utilizes cutting-edge technologies to seamlessly integrate them with modern applications.

  • Understanding what you want to achieve and how it aligns with your overall business goals.
  • Analyzing your legacy system’s architecture, data structures, and business rules.
  • Documenting data flow, structures, and processes and creating integration maps.
  • Choosing integration technologies and tools based on system requirements.
  • Planning for data migration, including mapping, transformation, and validation.
  • Addressing security concerns for data transfer and system access.
  • Developing a detailed plan with timelines, milestones, and responsibilities.
  • Implementing middleware or an integration platform if needed.
  • Conducting unit, integration, and system testing for various scenarios.
  • Implementing monitoring tools and establishing a maintenance plan.
  • Documenting the integration process and transferring knowledge to teams.
  • Planning for scalability and potential future expansions.

Areas of Expertise: Legacy System Integration Services for Various Industries


  • Talent acquisition software
  • Smart Background Checks
  • Payroll and benefits system integration
  • Performance management system
  • Time and attendance system
  • Applicant tracking system (ATS)
  • Learning management system (LMS)
  • Human Resources Information System (HRIS)
  • Reporting and People Analytics
  • Employee engagement platform


  • Core banking system
  • Payment gateway
  • CRM
  • Data warehousing integration
  • Mobile banking app
  • Blockchain integration
  • Accounting system
  • Wealth management


  • Claims workflow management
  • P2P Insurance platforms
  • Payment and Reconciliation
  • Mobile micro-insurance
  • Risk management


  • Food delivery apps
  • Self-service app
  • Loyalty management solutions
  • Hotel booking portals
  • Casino app
  • IoT device integration
  • Ticket management systems


  • Point of Sale (POS) integration
  • Inventory management system
  • CRM Integration
  • E-commerce platform integration
  • Supply chain management
  • ERP integration
  • Payment gateway integration
  • Data analytics and business intelligence
  • Customer loyalty program integration
  • Automated invoicing

👉 Learn the Art of Successful Legacy Application Modernization

Why Choose Our Legacy System Integration Services?

Our commitment to engineering excellence, combined with years of experience in legacy system integration, sets us apart in the world of software product development.

1. Experience and Innovation

At Azilen, we believe that true innovation is born from a delicate balance between experience and an unwavering commitment to pushing boundaries.

Our PRO Engineers bring years of hands-on experience in legacy system integration, coupled with a relentless drive for innovation!

2. Tailored Solutions

We understand that each business is as unique as a fingerprint.

That’s why we don’t offer generic solutions!

Instead, we craft bespoke strategies tailored to your specific needs and objectives.

3. Future-Ready Today, Not Tomorrow

At Azilen, we don’t just integrate legacy systems; we future-proof them.

Our forward-thinking approach involves not just addressing current challenges but anticipating and mitigating future ones.

4. The Art of Seamless Integration

We focus on orchestrating different systems rather than just making them work together.

This enables us to perform the integration process with a smooth transition, minimizing disruptions, and optimizing efficiency.

5. Over a Decade of Experience

Beyond legacy application modernization services, we offer an experience that exceeds the ordinary.

From the first consultation to the final implementation, we prioritize open communication, transparency, and collaboration.

We believe that successful legacy system integration is a joint effort, and our commitment to your success is unwavering.

So, let’s connect!

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