Legacy systems, the long-lived software or hardware solutions your organization has depended on for years can become roadblocks to innovation. When legacy systems can’t talk to cloud services or modern apps, teams resort to manual processes and workarounds.
Studies find that 64% of organizations still rely on legacy systems for at least 25% of their operations, and in 88% of companies these outdated technologies are hampering growth. To stay competitive, your organization must bridge old and new technology. This blog explains how to integrate legacy systems with modern applications, covering what legacy systems are, why integration matters, common challenges, and proven integration approaches (such as APIs or iPaaS).
What Is a Legacy System?
A legacy system is any existing software or hardware that an organization has used for many years and has since become outdated. These can include old databases, on-premises ERP or CRM programs, mainframe applications, or custom-built solutions. Legacy systems often lack modern, web-based interfaces and may not support up-to-date integration methods. For example, a legacy system might run on an unsupported mainframe or use proprietary protocols, making it difficult to plug into today’s cloud platforms. While these systems may still perform important tasks reliably, they typically don’t support RESTful APIs or modern user interfaces.
Disadvantages of Legacy Systems
Legacy systems pose several business and technical drawbacks. Even if they keep running, they often drain resources and introduce risk. Common disadvantages include:
Security and Compliance Risks
Legacy systems were built to old standards and may not receive security patches. This makes them vulnerable to breaches. A legacy system’s inability to meet today’s data standards (GDPR, HIPAA, PCI) can also invite regulatory penalties. Many legacy platforms have holes that attackers can exploit, and with vendors no longer supporting them, patches are unavailable.
High Maintenance Costs
Maintaining legacy code is expensive. Often 60–80% of IT budgets go into “keeping the lights on” for these systems. In banking, for instance, about 70% of IT budgets is spent just on legacy maintenance. These costs include specialized hardware, licenses, and scarce talent. With programming languages like COBOL, the developer pool is shrinking, hence, losing expertise makes fixes slow and costly.
Operational Inefficiency
Legacy systems frequently require manual intervention. Employees may need to export data into spreadsheets or re-key information to connect with newer systems. This not only slows processes but also introduces errors. Manual data transfer slows down business processes and introduces data errors, making efficiency a top reason to integrate. Studies also find that most reports in old BI systems go unused (one stat claims 97% are forgotten), meaning valuable data sits idle in legacy silos.
Outdated User Experience
Older systems often have clunky or minimal interfaces. They lack modern features like mobile access, rich dashboards, or self-service capabilities. In retail, this means an old inventory system might block a seamless online store experience. Without integration, your users may need separate logins or batch exports just to see inventory or customer data in a modern storefront.
Poor Scalability and Agility
Monolithic legacy software isn’t designed to scale with today’s loads. As workloads grow, legacy systems can become bottlenecks or crash under pressure. Also, adding new functionality (AI/ML, IoT support, etc.) to a legacy codebase is usually impractical. In a digital-first world, this hinders innovation.
Talent and Continuity Risks
When a few specialists understand a legacy system and they leave, your business continuity is at risk. Legacy customization makes systems brittle: other staff fear touching them and breakdowns become likely. Loss of institutional knowledge (e.g. code comments, process maps) means that even routine changes may require costly audits or trial-and-error.
What Is Legacy System Integration?
Legacy system integration means connecting an old system with modern software, so they work together seamlessly. Rather than ripping out the old system entirely, you create a bridge between it and new cloud services or applications. Depending on the technology, integration can happen via custom code, APIs, or middleware.
In practice, integration might involve building an API layer around the legacy app, using middleware or an ESB (Enterprise Service Bus) to route data, or employing a cloud iPaaS (Integration Platform as a Service) that provides connectors. The goal is to allow data and commands to flow between old and new systems without manual handoffs. For example, an inventory record in an on-prem legacy ERP could be automatically synced to a cloud-based e‑commerce platform, keeping both systems in sync. Integration aims to preserve the legacy system’s useful features (e.g. historical data or core transaction logic) while giving your organization the benefits of modern apps (analytics, UX, automation).
How to Connect Legacy Systems to Modern Apps
Once you decide to integrate, choosing the right approach is crucial. The method depends on what your legacy system supports and the scope of integration. Key options include:
API Integration
If the legacy system already exposes an API (or if you can build one), this is often the cleanest method. You use the API as a bridge, letting modern applications call legacy functions directly. Using existing APIs (with an integration platform) lets you sync data in near real time with minimal coding. For example, a legacy customer database with a read API could be polled by a cloud CRM to update customer details automatically. APIs ensure only relevant data is shared and can enforce security controls.
Database Connector Integration
When no API exists but you can query the legacy database, a database connector (via iPaaS or middleware) may work. This reads data from the legacy backend and writes it into modern systems. For instance, you might schedule reads on a legacy SQL server and push rows into a cloud warehouse. The drawback is you must understand the legacy data model well, or you risk misinterpreting coded values. Also, most connectors read-only, so writes back to the legacy database are usually avoided to prevent corruption.
File-Based Integration
Legacy systems often can import/export CSV, XML or other file types. With this approach, integration happens by regularly exchanging files. For example, the legacy ERP might dump orders to a CSV file each night, which is then loaded into a modern order management app. This is simple and reliable, but it doesn’t offer real-time sync. Data is batched on a schedule (hourly, nightly). File transfer is a common fallback if APIs/connectors are impossible, but it means updates aren’t instantaneous.
Service Layer (Middleware) Integration
Here you add a middleware layer on top of the legacy system. This layer can transform and validate data flows in both directions. For instance, you might build a microservice that wraps legacy functions and presents a modern interface. The service layer takes legacy output, restructures it, and feeds it to the new app. Conversely, it can take new app requests and translate them to legacy API calls or database queries. This approach is flexible and powerful but requires building or configuring additional software.
Integration Platform as a Service (iPaaS)
For broad integration across many systems, an iPaaS is ideal. iPaaS offerings provide a visual interface, pre-built connectors (including some for common legacy tech), and workflow tools to integrate systems. With iPaaS, you can orchestrate multiple data flows, transformations, and even business rules centrally. The platform handles much of the plumbing, which speeds development. For example, BURQ is a modern iPaaS that connects ERP, CRM, marketplaces and more. iPaaS solutions often include security and logging features out of the box. Just ensure your chosen iPaaS supports your specific legacy formats.
Each method has trade-offs. APIs and iPaaS support real-time communication but may require more setup. File or database integration is simpler but near real-time at best. Often a hybrid is used: a legacy ERP might push nightly files for large data loads but also have key APIs for critical transactions. The right approach depends on factors like how often data must move, how much custom coding you can do, and whether the legacy vendor offers any connectors or APIs.
What Happens When You Integrate Legacy Systems with Modern Apps
Integrating legacy and modern systems unlocks real business value. Once connected, your old and new tools work together, yielding several benefits:
- Better Use of Data: After integration, data trapped in legacy silos becomes available company wide. For example, customer records in an old CRM can flow into modern analytics tools. Integration makes legacy customer data better used, enabling personalized services and insights. You can run real-time dashboards pulling from both old and new sources, giving you a complete view of operations.
- Automated Workflows and Efficiency: Many manual tasks disappear. Integration often means setting up automated triggers, when an event happens in one system, another system responds. As a result, employees spend less time on routine transfers and more on high-value work. For instance, a legacy order system that automatically notifies the inventory app and finance app cuts weeks of back-and-forth.
- New Functional Capabilities: Older systems may not be scalable or secure by themselves, but integration lets you augment them. You can gradually introduce features like cloud backups, advanced analytics, or AI. For example, by pushing legacy data into a cloud platform, you may gain elastic storage and built-in security patches. Or by exposing legacy services via an API gateway, you can add modern authentication and monitoring on top of them.
- Eliminate Data Silos: Fragmented data is a common legacy problem. Integrating removes these silos, since information flows freely. A bank, for instance, could sync its legacy core banking system with a digital lending platform, ensuring customer data is consistent everywhere. This not only improves decision-making (everyone is “looking at the same data”) but also enhances customer experience by preventing app hopping.
- Future-Proofing and ROI: Integration is not just a short-term fix. Over time, it makes your IT environment more flexible. Each new project can reuse the integration infrastructure you’ve built. As cited earlier, organizations often save time and cost on subsequent projects by having an API or integration layer in place. In addition, many integration projects pay for themselves by freeing up teams to innovate rather than maintain old systems. One Forrester study found that integration tools could deliver hundreds of percent ROI in only a few years. For example, Azure Integration Services reportedly delivered 295% ROI with <6-month payback. Hence, connecting your legacy systems can help in achieving long-term financial goals.
Final Thoughts
Legacy IT will always be part of your organization’s landscape, but it doesn’t have to hold you back. By carefully integrating old systems with new cloud applications, you can preserve valuable data and processes while unlocking modern capabilities. We’ve covered why integration matters, the challenges you’ll face, and the key approaches (APIs, connectors, service layers, iPaaS) to make it happen. The path you choose depends on your systems and goals, but one thing is clear: strategic integration beats blindly modernizing without a plan.
Ready to turn your legacy systems into an asset for innovation? BURQ offers a low-code/no-code iPaaS platform designed to connect your legacy software with today’s applications. Whether you need real-time API sync, batch data flows, or secure transformation layers, BURQ can unify your ERP, CRM, marketplaces, and more.
Visit BURQ to explore how your organization can integrate its legacy systems with modern technology and achieve scalable, secure growth.
FAQs
Q1. What is the cost of legacy system integration compared to full system replacement?
Legacy system integration is usually more cost-effective than replacing an entire system. Integration lets you connect existing software with modern apps without disrupting core processes, while replacement often involves higher licensing fees, data migration risks, and lengthy downtime.
Q2. Can legacy systems be integrated with cloud-native applications securely?
Yes. By using APIs, middleware, or iPaaS platforms with built-in encryption and access controls, organizations can securely connect legacy systems to modern cloud applications while ensuring compliance with standards like GDPR.
Q3. How long does it take to integrate legacy systems with modern apps?
The timeline depends on the method chosen (API, connectors, iPaaS) and the complexity of the legacy system. Simple integrations can take weeks, while complex, multi-system integrations may take several months.
Q4. Do I need to modernize my legacy system before integration?
Not always. Many organizations integrate legacy systems “as-is” by using an API wrapper or iPaaS. However, if the system is unstable or lacks reliable data outputs, a modernization step may be necessary before integration.
Q5. What industries benefit most from legacy system integration?
Industries such as banking, healthcare, retail, and manufacturing benefit greatly. Integration allows them to connect core systems like ERPs, CRMs, or EMRs with modern apps for analytics, automation, and improved customer experiences.
Q6. How does iPaaS simplify legacy system integration?
iPaaS platforms provide pre-built connectors, low-code workflow design, and security features, reducing the complexity of building custom integrations. This helps organizations quickly connect legacy systems with modern apps at scale.
