Modernizing Legacy Banking Systems with Sapient Slingshot – From COBOL to Cloud-Native

In today’s rapidly evolving financial landscape, legacy banking systems—often built on decades-old technologies like COBOL—pose a significant barrier to innovation, agility, and customer-centricity. These systems are complex, tightly coupled, and costly to maintain, making modernization a daunting prospect for even the most forward-thinking banks. Yet, the imperative to transform is clear: to remain competitive, banks must embrace modern, cloud-native architectures that enable continuous evolution, regulatory compliance, and superior customer experiences.

The Challenge: Legacy Systems Holding Banks Back

Many banks still rely on core applications written in COBOL and other legacy languages. These systems, while robust, are inflexible and difficult to adapt to new business requirements or regulatory changes. Traditional modernization efforts can drag on for years, consuming vast resources and introducing significant risk. The result? Innovation stalls, operational costs rise, and customer expectations go unmet.

The Solution: Sapient Slingshot’s AI-Driven Modernization

Sapient Slingshot, Publicis Sapient’s proprietary AI-powered platform, is purpose-built to accelerate and de-risk the modernization of legacy banking applications. Leveraging advanced AI agents, a vast enterprise code library, and deep domain expertise, Slingshot transforms the modernization journey from a high-risk, multi-year slog into a streamlined, iterative process that delivers results in a fraction of the time.

How It Works: From COBOL to Cloud-Native in Three Core Steps

Code to Spec:
Slingshot begins by analyzing legacy codebases—such as millions of lines of COBOL—using AI to break down and understand the program logic, data structures, and business rules. This analysis is translated into tech-neutral specifications and clear, behavior-driven requirement documents. The result is a transparent, easily understood blueprint that product owners and developers can review, enhance, and sign off on.
Spec to Design:
Once specifications are validated, Slingshot’s AI generates modern architecture diagrams tailored to the bank’s target state. This includes high-level microservices architectures, entity-relationship (ER) diagrams, sequence diagrams, and class diagrams. These design artifacts provide a clear roadmap for the new system, ensuring alignment with business goals and regulatory requirements.
Design to Modern Code:
With the architecture in place, Slingshot’s AI agents generate modular, production-ready code in modern languages such as Java. The platform also creates comprehensive unit tests, automation test scripts, and API documentation (including Swagger specs for REST APIs). Automated static code analysis and functional test suites ensure the new codebase is robust, secure, and ready for deployment.

Risk Reduction and Compliance by Design

Modernizing core banking systems is fraught with risk—from data integrity and business continuity to regulatory compliance. Sapient Slingshot addresses these challenges head-on:

Iterative, Agile Approach: Each phase of the modernization journey is meticulously planned and executed, allowing for continuous feedback, risk mitigation, and agile decision-making.
Automated Testing and Validation: Built-in test automation and static code analysis reduce defects and ensure the new system meets stringent quality and compliance standards.
Regulatory Alignment: Automated compliance checks and documentation generation help banks stay ahead of evolving regulatory requirements, reducing the risk of costly compliance gaps.

Accelerating Time-to-Value

By automating the most complex and error-prone aspects of legacy modernization, Sapient Slingshot dramatically accelerates timelines. What once took years can now be achieved in months or even weeks, freeing up IT and business teams to focus on innovation and customer value. Banks benefit from:

Reduced technical debt and future-proofed infrastructure
Faster time to market for new products and services
Improved code quality and consistency
Enhanced productivity and resource optimization

Supporting Continuous Evolution

Modern banking demands continuous evolution—not just a one-time upgrade. Sapient Slingshot’s agentic AI architecture and enterprise code library enable ongoing enhancements, seamless integration with cloud platforms, and support for new business models. Banks can adapt quickly to market changes, regulatory updates, and customer expectations, ensuring long-term competitiveness.

Real-World Impact: IT Modernization Portal

The IT Modernization Portal, powered by Sapient Slingshot, provides banks with a self-guided, transparent pathway from legacy to modern architectures. It streamlines every step of the transition, reducing risk, accelerating delivery, and improving code accuracy. Banks leveraging this approach have seen significant reductions in modernization timelines and defect rates, enabling them to deliver new digital experiences faster and more reliably.

Why Publicis Sapient?

With a track record of working with 85% of the top global banks, Publicis Sapient combines advanced technology with deep industry insight. Sapient Slingshot is more than a tool—it’s a proven platform for core modernization, designed to help banks unlock agility, efficiency, and innovation at scale.

Ready to modernize your legacy banking systems?

Connect with our experts to see how Sapient Slingshot can accelerate your journey from COBOL to cloud-native—and position your bank for the future.