VB6 to C# Modernization for a Financial Institution: 70–80% Faster Conversion, AWS-Native and Compliance-First

Results at a Glance

Engagement Snapshot

About the client:

The client is a leading financial institution based in Salt Lake City, recognized for its commitment to security and compliance in financial services. Their critical systems required modernization to meet evolving industry demands, but any migration had to maintain strict compliance with financial regulations throughout.

The client needed a fast, reliable path from VB6 to C# that would improve security and scalability without compromising regulatory compliance at any point during the transition.

Challenge

The client’s legacy VB6 system presented four constraints that made modernization both urgent and high-risk:

Security Vulnerabilities in a Regulated Financial Environment

The aging VB6 system carried security vulnerabilities that created exposure in an environment governed by strict financial regulatory standards. Addressing these vulnerabilities was a primary driver for the modernization initiative.

Scalability Limitations Under Compliance Constraints

The legacy architecture could not scale to meet evolving business demands, but any changes to the system had to remain within the bounds of financial compliance requirements. This meant that modernization could not take shortcuts, as every architectural decision had to satisfy both scalability goals and regulatory constraints simultaneously.

Inadequate Documentation Blocking Safe Migration

The VB6 codebase lacked adequate documentation, making it difficult to map business logic, dependencies, and integration points. Without comprehensive documentation, planning a safe migration path was slow and error-prone, and the risk of losing critical business logic during transformation was high.

Complex Business Logic Requiring Exact Preservation

The financial system contained complex business logic that had to be preserved exactly during migration. In a financial institution, even minor deviations in business logic can create compliance violations, reporting errors, or transaction inaccuracies. There was zero tolerance for logic loss.

How Legacyleap Modernized VB6 to C# with an AWS-Native Approach

Legacyleap used Gen AI-powered automation combined with four AWS services to deliver the migration. Each service played a specific role in the modernization pipeline:

Amazon Bedrock: Code Comprehension and Translation

Amazon Bedrock provided the AI foundation for analyzing and translating the VB6 codebase. Advanced large language models comprehended the legacy code structure, extracted business logic, and generated accurate C# translations, addressing the documentation gap by making the codebase understandable before any transformation began.

Amazon Neptune: Code Relationship Mapping

Amazon Neptune was used as a vector database to manage and maintain the relationships between legacy and modernized code components. This relationship mapping ensured that dependencies, integration points, and business logic connections were tracked throughout the migration, so nothing was lost or orphaned during transformation.

AWS Glue: Data Migration and ETL

AWS Glue handled data migration and ETL processes, ensuring that the transition from legacy data structures to the modernized environment was seamless and did not interrupt operations. Data integrity was maintained throughout the migration.

Amazon CodeGuru: Code Quality Optimization

Amazon CodeGuru was integrated to optimize the quality and performance of the newly generated C# code. CodeGuru’s analysis identified performance bottlenecks, security issues, and code quality improvements, ensuring the modernized codebase met production standards from day one.

Financial Compliance Throughout

The client operates under stringent financial regulatory standards. Legacyleap’s approach maintained compliance at every stage: Amazon Bedrock preserved business logic during translation, Amazon Neptune tracked all code relationships to prevent logic loss, and Amazon CodeGuru validated code quality and security. The modernized C# platform improved the client’s overall security posture compared to the legacy VB6 system.

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