Banking Card Operations Platform

C#.NETVB6SQL ServerSFTPBackground Services

The Challenge

East West Banking Corporation processes card operations for hundreds of thousands of customers. When I joined, many critical workflows were manual — operators ran ETL jobs by hand, encrypted files manually before SFTP uploads, and relied on legacy VB6 applications that only a handful of people understood. These manual processes were slow, error-prone, and a bottleneck as card volume grew.

What I Built

Automated ETL & File Processing: Replaced manual ETL processes with C# background services that ran on schedule — extracting data from card systems, transforming it into the formats required by partner banks and payment networks, encrypting files, and uploading them via SFTP. What used to take operators hours of careful manual work now ran unattended with full logging and error notification.

SQL Query Optimization: Audited and rewrote the SQL queries behind critical card operations reports. Some of these reports had grown organically over years and were hitting the database harder than necessary. Targeted optimizations — index tuning, query restructuring, eliminating unnecessary joins — delivered significant performance improvements.

Legacy VB6 Migration: Migrated legacy VB6 applications to the modern .NET stack. These were applications that had been running for years with minimal documentation. Each migration involved understanding the existing business logic, writing it cleanly in C#, and validating that the new version produced identical results before cutover.

Web Services Maintenance: Maintained and enhanced web services for card operations — transaction processing, balance inquiries, card activation workflows — ensuring reliability for systems that other departments depended on daily.

Impact

  • Automated ETL eliminated hours of manual work per day and removed human error from file processing
  • SQL optimizations cut report generation times significantly
  • VB6-to-.NET migrations brought legacy systems under modern source control and testing practices
  • Background services ran 24/7 with alerting, replacing "someone has to remember to do this" workflows

What I Learned

Banking taught me operational discipline. When your code processes financial transactions, there is no room for "it works on my machine." Every change needs to be auditable, every failure needs to be recoverable, and every process needs to run whether or not someone is watching. The automation work here was not glamorous, but it was some of the most impactful engineering I have done.