Financial Services Modernization on Google Cloud

Banks and financial institutions face a modernization challenge unlike almost any other industry. Core banking platforms, payments-adjacent systems, servicing applications, API estates and regulatory workflows are deeply interconnected, business-critical and difficult to change without introducing risk. Decades of embedded business logic often sit inside legacy code, undocumented dependencies and manual operational workarounds. The result is familiar: higher maintenance costs, slower delivery, rising technical debt and a growing gap between what the business needs and what the technology estate can safely support.

Publicis Sapient helps financial institutions modernize these environments on Google Cloud with a practical, governed and incremental approach. Rather than forcing risky big-bang replacement, we help banks modernize in controlled stages—preserving the logic that still matters, reducing disruption and creating a stronger foundation for cloud-native delivery, data activation and future AI adoption.

Modernization for regulated environments

In financial services, modernization cannot be treated as a simple migration or code conversion exercise. Core systems must continue to support customer trust, transaction integrity, operational resilience and regulatory obligations while they change. That means modernization programs have to balance speed with control, and innovation with explainability.

Publicis Sapient approaches modernization as a business-led transformation tied to measurable outcomes such as faster delivery, lower disruption, improved resilience and stronger agility. For banks, this is especially important in areas such as core banking, product servicing, customer platforms, partner connectivity and payments-related processes, where failure risk is high and undocumented behavior can create major downstream consequences.

Our focus is not just on moving workloads to the cloud. It is on helping financial institutions modernize legacy applications and infrastructure in a way that supports compliance, data privacy, auditability and day-to-day continuity.

Preserve critical business logic before you change it

One of the biggest risks in financial services modernization is losing the logic that makes the system work. Business rules for pricing, reconciliation, settlement, servicing, reporting, exceptions and controls are often buried in legacy applications and understood by only a shrinking pool of specialists.

That is why Publicis Sapient starts with clarity. Using Sapient Slingshot and human-assisted AI, we help banks analyze legacy code, uncover rules and dependencies, and convert existing applications into verified, business-readable specifications. This specification-led approach creates a trusted bridge from current-state systems to future-state design.

This matters most in banking environments where “mostly correct” is not good enough. Modernization has to be explainable, testable and aligned to the controls the business depends on.

AI-assisted acceleration with human control

Publicis Sapient uses human-assisted AI to accelerate some of the hardest parts of legacy modernization: code transition, documentation, specification generation and automated testing. The model is designed to increase speed and productivity without turning modernization into a black-box process.

Engineers, architects and business stakeholders remain in control throughout the journey. They validate outputs, confirm business intent, shape the target architecture and approve production readiness. This human-in-the-loop model is particularly valuable for financial institutions that need modernization to be auditable and aligned to internal governance standards.

Sapient Slingshot supports this journey by turning legacy code into clear specifications, then using that specification layer as the source of truth for modern design and code generation. Publicis Sapient has demonstrated up to 99% code-to-spec accuracy, 3x faster migration and 50% savings in modernization costs through this approach. In a banking modernization effort, Slingshot analyzed nearly three million lines of COBOL and turned hidden business rules into structured specifications, giving the institution a clearer and safer path toward modernization.

Accelerate testing and reduce release risk

For financial institutions, modernization risk does not end once requirements are understood. Every transformed system must be validated against expected behavior across standard flows, edge cases, integrations and compliance-sensitive scenarios.

Publicis Sapient uses AI-assisted testing to expand coverage, generate test assets faster and strengthen confidence that modernized applications remain aligned to original business behavior where required. Because specifications, transformed code and testing artifacts are connected, teams gain better traceability across the delivery lifecycle.

This helps banks reduce regression risk, improve release quality and move faster with greater assurance—especially when modernizing core services, high-volume interfaces and transaction-related systems that cannot tolerate functional drift.

Modernize API estates without rebuilding everything at once

For many financial institutions, APIs are the practical layer that connects modernization to business value. They help expose capabilities securely, connect legacy and modern services, support ecosystem integration and power new customer and partner experiences without requiring every platform to be replaced at the same time.

Publicis Sapient helps banks unlock the value of their API estates through secure, scalable and developer-friendly API management on Apigee. This enables a more modular modernization path, where institutions can modernize incrementally by domain, product, feed or service rather than relying on a single cutover event.

This approach is especially relevant for payments-adjacent transformation, where orchestration, connectivity, real-time service integration and secure data exchange often need to evolve alongside—rather than after—core system change. Publicis Sapient also worked with Lloyds Banking Group and Google to design and implement an API management platform on Google Cloud Platform aligned to the bank’s API strategy using Apigee.

Build secure cloud foundations on Google Cloud

Modernized applications need a modern landing environment. Publicis Sapient’s Cloud Acceleration Platform provides a governed cloud foundation for Google Cloud with pre-defined templates, integrated tooling, workload-specific landing zones and robust security controls.

For financial services organizations, CAP helps accelerate secure cloud adoption while supporting the controls that regulated environments require. Publicis Sapient positions CAP as a secure, compliant and automated cloud foundation with workload-specific landing zones, automated compliance monitoring, AI-driven risk assessment and more than 68 built-in controls for financial services contexts.

Combined with a security-by-design approach, CAP helps banks establish repeatable foundations for modernization without sacrificing governance. Publicis Sapient embeds security controls into workflows and applies Zero Trust principles such as least-privilege access and ongoing verification. The result is a more resilient path to Google Cloud for business-critical workloads.

From legacy estate to cloud-native banking platforms

Publicis Sapient connects application modernization, infrastructure modernization and delivery transformation into one governed journey on Google Cloud. That journey can include:

This is how banks move beyond lift-and-shift. Not by simply relocating old constraints, but by creating a modern operating model that is more scalable, resilient and easier to improve.

Modernize incrementally, modernize with control

Financial services leaders do not need another transformation story built around unnecessary risk. They need a modernization model that protects critical business logic, respects compliance obligations and delivers progress without destabilizing live operations.

Publicis Sapient helps banks and financial institutions modernize core systems, API estates and payments-adjacent capabilities on Google Cloud with greater speed, traceability and control. By combining human-assisted AI, Sapient Slingshot, secure cloud foundations through CAP and deep modernization expertise, we help clients reduce technical debt while building a stronger foundation for resilience, innovation and long-term digital business transformation.