GenAI-Powered App Modernization

GenAI-driven application re-imagination using AI coding assistants for a global investment and insurance company

HCLTech accelerated legacy application transformation with automated code generation, structured workflows and improved development consistency.

5 min read

Overview

For a leading financial institution, modernizing customer-facing applications was critical to improving digital experience and maintaining operational agility. With more than 1,000 screens built on legacy technologies such as XSL, Dust and JSF, the existing landscape had become increasingly complex to maintain and scale. The tightly coupled architecture and varied technology stack made modernization efforts resource-intensive and difficult to standardize.

To address these challenges, the organization explored how GenAI-led automation and Vibe Coding could support a faster and more structured modernization journey. HCLTech partnered with the client to demonstrate how an automation-led approach could help streamline the migration of legacy screens to a modern platform, reduce manual work and ensure greater consistency across development, testing and quality checks.

The Challenge

The client’s applications were built on multiple legacy technologies, creating a complex environment that was difficult to modernize at scale. Business logic was tightly linked to the user interface and documentation was limited, requiring teams to manually analyze and interpret each screen before migration.

Given the scale of the modernization program, the process relied heavily on manual analysis, code rewriting and testing. This increased delivery effort and created the risk of inconsistencies and quality drift across the program.

As the program expanded, maintaining alignment with customer-specific frameworks, libraries and development standards also became challenging, making it harder to scale the modernization effort while ensuring quality and consistency.

The Objective

The objective was to modernize a large set of customer-facing screens while transitioning from legacy technologies to a modern platform. The client aimed to decouple business logic from the user interface, accelerate delivery timelines and reduce the manual effort involved in analyzing, rewriting and testing legacy code.

At the same time, it was important to ensure that the modernization process remained consistent and aligned with the client’s specific frameworks, libraries and development standards and overall enterprise architecture principles.

The Solution

To address these challenges, the organization adopted a GenAI-powered engineering approach, combining automation-first accelerators, persona-based workflows and curated prompts to streamline modernization activities across the SDLC.

Automation-first modernization

A suite of GenAI-driven vibe recipes automated key stages of the modernization lifecycle. These recipes included:

Logic blueprint – Extracts and documents business logic from legacy screens.
Spec generator – Converts extracted logic into structured API specifications.
API code generator – Generates backend service code aligned with modern frameworks.
Documentation – Creates structured documentation and supporting artifacts.
UI code generator – Generates modern UI code compatible with custom frameworks.
Code reviewer – Performs automated quality and compliance checks.
Test generator– Generates and executes functional and API test cases.

Together, these accelerators automate analysis, mapping, code generation, validation and testing, significantly reducing manual effort across the lifecycle.

Persona-based transformation workflows

The modernization process was structured around role-specific workflows to ensure clarity and efficiency:

Business Analysts used analyst recipes and prompt libraries to perform page analysis, extract business logic and document navigation flows.
Architects leveraged designer recipes to convert extracted logic into OpenAPI specifications, establishing the foundation for modern API-based architecture.
Developers utilized development recipes to automatically generate Java Spring services and UI code, ensuring compatibility with customer-specific frameworks.
Testers applied testing recipes to generate and execute functional and API test cases, enabling early validation and defect detection.

Curated prompts for structured automation

Each persona used predefined prompt libraries tailored to their tasks. These curated prompts guided the GenAI accelerators to produce standardized artifacts such as:

Business logic maps
API specifications
Backend and UI code
Functional and integration test cases

This structured approach ensured consistent outputs, minimal manual rework and faster iteration cycles.

The Impact

The GenAI-driven engineering approach delivered measurable gains in delivery speed and software quality:

50% increase in time-to-market through automation-led development and faster lifecycle execution.
40% reduction in System Integration Testing defects, driven by standardized code generation and early validation.

The automation-first strategy significantly reduced manual effort across analysis, development and testing, enabling teams to modernize applications at scale without compromising quality.

Beyond The Numbers

The client valued the greater consistency and reliability this approach brought to the modernization program. With structured workflows and automation across key stages, the process became more predictable and easier to manage at scale, strengthening confidence in delivery outcomes.

HCLTech delivered more than improvements in speed and productivity. The initiative established a repeatable modernization framework that improved architectural consistency, enhanced collaboration across roles and enabled teams to focus more on innovation than repetitive migration tasks. Beyond measurable results, it created a scalable foundation for future modernization initiatives while maintaining strong governance and quality standards.

Celebrating Success

With a GenAI-driven engineering approach, what was once a complex and effort-intensive modernization effort evolved into a more streamlined and scalable transformation program. Legacy screens were successfully transitioned to a modern platform while maintaining consistency, quality and alignment with enterprise standards.

This collaboration with HCLTech demonstrates how GenAI-enabled development approaches can simplify large-scale modernization while improving delivery efficiency and code quality. The program enabled faster delivery, stronger code quality and a more efficient development lifecycle.

With these capabilities in place, the client is now better positioned to continue modernizing applications and exploring AI-led innovation across its technology landscape, supporting more agile development and improved digital experiences.