Mark Johnson

Software developer with 20+ years of experience delivering quality software in dynamic environments. Proven track record of adapting codebases to microservices architecture with continuous enhancements. Led design and implementation of a database schema service that enabled a shift from quarterly updates to near-continuous deployment.

Active Public

Trust security clearance. Experienced with AI-assisted development tools including GitHub Copilot.

Senior Software Developer at J-Mack Technologies, LLC (2024-05 – Present)

Veterans Administration (VA) – Digital Modernization

• Upgraded document storage capabilities by migrating monolithic software to microservice architecture on the VA website.
• Implemented new REST API calls across multiple distinct codebases including Awards, Ratings, and Exam Management modules.
• Active Public Trust security clearance required and maintained for this engagement.
• Participated in agency-wide GitHub Copilot pilot program, integrating AI-assisted development into daily workflow.

Senior Software Developer (SW Design Engineer II) at SAP Concur (2013-04 – 2024-05)

• Developed and maintained microservices using Java, Spring Boot, and Kubernetes, with Docker and Helm for containerization and deployment.
• Implemented multi-threaded Java applications to optimize Extract, Transform, and Load (ETL) data processing performance across expense and travel databases, integrating results into a single database used by IBM Cognos reporting.
• Designed and built a REST API service using Liquibase to automate database creation and schema updates, accelerating database change turnaround from quarterly to near-continuous delivery.
• Deployed a MySQL database via AWS CloudFormation template — including the dependent service — to the Japan data center within a single two-week sprint.
• Resolved custom data load failures using staging tables and code changes, uncovering multiple hidden issues in SQL Server PIVOT table behavior.
• Contributed a bug fix to the Liquibase open-source project, correcting a NullPointerException in production code.
• Maintained highest ticket close rate on the team providing second-tier customer support on data issues.
• Authored and maintained JUnit and Mockito unit tests; used CI/CD pipelines to automate build and deployment. Performed GitHub code reviews for functional and standards compliance.
• Mentored junior and mid-level developers; active contributor in Agile/Scrum environment using Jira for issue tracking.

Software Engineer at CGI Federal (2003-09 – 2013-03)

• Developed and maintained a client-server application for vehicle repair work orders, parts ordering, inventory, employee time management, project finance, and demand analysis using C#, T-SQL, Crystal Reports, and Delphi.
• Built and enhanced a handheld (Windows Mobile) application in C# for inventory tracking, time sheet management, and barcode-based parts receiving; integrated with the main application via Sybase MobiLink.
• Designed and developed the C#/.NET interface between the application and the Crystal Reports engine; created stored procedures and report templates while working within DOD database connection limits.
• Extended base components with new functionality reused across multiple projects; significant contributions to parts subsystem grouping and user interface improvements.
• Diagnosed and resolved memory errors in third-party component libraries; maintained development environment databases (Sybase SQL Anywhere) and managed database backup cataloging.
• Major contributor to team coding standards development; mentored junior developers and performed code reviews.

Programmer/Analyst at Patient Care Technologies (2002-09 – 2003-09)

• Maintained back-office accounting system for home health agencies, covering software development, data integrity management, and first-level customer support.
• Application developed in Magic (a LISP-based proprietary language); responsible for ongoing feature maintenance and data quality.

Bachelor of Science in Computer Science