# Leon Tzeng > Senior Full Stack Software Engineer .Net |, TypeScript (React) Location: Pasadena, California, United States Profile: https://flows.cv/leontzeng ## Work Experience ### Senior Software Engineer @ Paylocity Jan 2023 – Present Spearheaded migration of critical WorkEngine job processing system from V3 to V6, implementing pre/post-deploy DACPAC scripts with comprehensive rollback procedures to ensure zero-downtime upgrades, enabling enhanced observability through Datadog logging and priority-based job execution for improved system reliability. Led full-stack modernization of legacy Angular reporting application to React/TypeScript, architecting Redux state management patterns for a dynamic report builder supporting Csv/Pdf/Xlsx exports, advanced filtering, grouping, and role-based security grains to protect sensitive data across enterprise user base. Deployed via Teamcity pipelines and leveraging Docker for local service containerization. Designed and delivered customer-facing reports synthesizing data from Snowflake data warehouse, building end-to-end pipelines that transform and present complex datasets to users through intuitive React interfaces, ensuring data accuracy and performance at scale. Refactored synchronous API endpoints to asynchronous patterns across multiple C# backend services, enabling company-wide consolidation into a unified React mono-repo and improving scalability for high-traffic reporting workloads. ### Software Engineer (Backend) @ Pie Insurance Jan 2022 – Jan 2023 | Washington, District of Columbia, United States Migrated several applications from .NET Core 2.2 to .NET 6, modernizing the tech stack. Developed new features for Workers Compensation Policy Reporting Specifications application in Golang to support compliance and regulatory adherence needs. Utilized AWS services (Lambdas, Step Functions, Dynamo, AppSync, CDK, etc) to develop typescript applications, including a remittance file processor. Features include file parsing, email generation and sending, and incorporation of third-party APIs. ### Senior Software Engineer @ Mastercard Jan 2021 – Jan 2022 | Arlington, Virginia, United States Enhanced the reliability and stability of a critical internal distributed application that processes an average of over a million jobs per day, by implementing a three-tier farming algorithm for JobQueue to prevent resource starvation. Transitioned clients from username/password login to SAML2 Single Sign-On authentication, by developing routes in the authentication/login applications and collaborating closely with cross-functional teams. Utilized expertise in .NET Core to upgrade multiple applications, including refactoring obsolete and unsafe code, implementing deprecated features, applying logging standards, and creating/modifying unit tests. Developed several command-line commands that streamlined development processes and significantly increased developer productivity. Participated in monthly on-call duties, mentored junior developers, fixed critical bugs, guided colleagues in cross-team concerns, and ensured the uptime of several critical applications via xMatters, Slack, and DataDog alerts. ### Software Engineer @ Homesnap Jan 2021 – Jan 2021 | Bethesda, Maryland, United States Led the development of several .NET asynchronous REST-ful microservices, including the Waze Ads API, enabled lower price points for real-time bidding and drove usage over 50%. Leveraged RabbitMQ technologies to migrate monolithic auto-complete data set into separate databases, resulting in faster load times and horizontal scaling. ### Web Application Developer @ AOPA Jan 2018 – Jan 2021 | Frederick, Maryland Member Acquisition (SAP BODS, SQL, Python, C#, Salesforce Marketing Cloud) Designed and implemented components of a new member acquisition pipeline (SAP BODS, SQL, Python, and C#) to funnel new members into Salesforce Marketing Cloud. Pilot Passport (Web API, SQL Server) Developed stored procedures and async controller routes using Web API and SQL Server that enabled photo uploads in a gamified Ionic mobile application, resulting in increased user engagement. Aopa.org/destinations/ (Angular 2, .NET MVC, Sitecore) Established a .NET MVC application that dynamically created kneeboards Created custom angular components that detailed relevant information about airports and it's related businesses Created custom Sitecore pages supporting non-profit needs ### Software Engineer @ DealerOn, Inc Jan 2017 – Jan 2018 | Derwood, Maryland Worked to support the in house existing Content Management System Upgraded the Riak database migrating raw ADO.NET queries to ElasticSearch, resulting in a a faster search times. (about 50%) Designed and implemented user tracking software in custom pages to enhance user experience and increase engagement. Developed a new editor in the CMS, increasing the efficiency of the design team and enabling faster turnaround times for features. ### Software Developer @ IHS Markit | Technology Jan 2014 – Jan 2017 | Rockville, Maryland, United States Demand Report (Sql Server Reporting Services and C#) Created a new report which provided information regarding gasoline consumption in the USA Researched and collaborated with database developers to architect database structures and build executables to ETL Fuelinsights.gasbuddy.com (Durandal and Entity Framework) Developed a MVVM website that gets a snapshot overview of current retail gas prices within the United States and Canada (Full stack) Utilized JQuery, Knockout, RequireJS, Bootstrap, Leaflet, and Highcharts to display data on front end in heat map and charts. Built back end services with solid principles using Entity Framework, Web API, and Redis. ### Sofware Developer Intern @ OPIS Jan 2013 – Jan 2013 | Gaithersburg, MD ## Education ### Bachelor of Science (BS) in Mathematics and Computer Science University of Maryland Jan 2011 – Jan 2014 ## Contact & Social - LinkedIn: https://linkedin.com/in/ltzeng --- Source: https://flows.cv/leontzeng JSON Resume: https://flows.cv/leontzeng/resume.json Last updated: 2026-03-22