Software Engineer Full-Stack
Resume:
JONATHAN
BARBALAS
Chicago, IL *****
*********@*****.***
https:/www.linkedin.com/in/jonathan-
barbalas-3492a15a
Summary
Results-oriented Software Engineer with 10+ years of full-stack experience building scalable web platforms using React and C# .NET. Improved system performance by up to 35% and accelerated development cycles by 20% through microservices, modern UI frameworks, and cloud-native design. Proven impact across high-traffic platforms at Instacart, Eversight, Capital One, and CME Group.
Education
Bachelor of Science – Computer Science
Wheaton College, Wheaton, IL
Graduated: Sep 2014
Experience
Software Engineer Instacart
SEP 2022 – PRESENT: REMOTE
Developed React-based interfaces for the cart, checkout, and delivery modules, improving user task flow completion rates by 28%.
Rewrote legacy ASP.NET APIs into modular .NET 8 microservices hosted on AWS Lambda and API Gateway, enhancing reliability under high load.
Introduced GraphQL endpoints for the cart system to streamline data fetches and reduce client-side complexity.
Built comprehensive unit and integration tests using NUnit and Moq, increasing test coverage from 60% to 90%.
Automated deployments via GitHub Actions and containerized services with Docker, reducing release times by 50%.
Implemented real-time order updates using WebSockets for delivery status, improving user engagement metrics.
Partnered with design and data teams to implement A/B tested UI improvements, boosting conversion by 15%.
Participated in system observability revamp using Datadog and OpenTelemetry, cutting incident response time in half.
Mentored junior engineers in React patterns and .NET architecture, improving onboarding success and reducing PR cycle times.
Software Engineer Eversight
OCT 2020 – SEP 2022: CHICAGO, IL
Engineered intelligent pricing UI components in React and Material UI for retailer-facing analytics dashboards.
Designed and implemented C# ASP.NET Core APIs to expose ML pricing insights and historical data.
2
Created real-time synchronization features using SignalR for collaborative pricing strategy development.
Refactored authentication flows with OAuth2.0 and JWT for improved security and single sign-on support.
Collaborated with DevOps to containerize backend services with Docker and deploy to ECS using Terraform.
Enhanced SQL Server stored procedures and indexing strategies, cutting load times on bulk data queries by 40%.
Led the effort to integrate Redis caching, eliminating 60% of redundant pricing calculations.
Automated end-to-end testing with Cypress for critical workflows, reducing QA cycles by one week.
Co-led biweekly roadmap sessions, aligning technical goals with business needs and client feedback.
Sr. Software Engineer Capital One
APR 2019 – OCT 2020: GREATER CHICAGO AREA
Built and maintained React-based UIs for customer portals, integrated with .NET Core APIs supporting card features and fraud alerts.
Devised RESTful services for credit eligibility checks and real-time transaction visualizations.
Orchestrated multi-step form wizards and profile components using Formik and custom hooks, reducing support tickets by 20%.
Adopted CQRS and MediatR in .NET backend to separate read/write workloads for the account API layer.
Architected event-driven workflows using RabbitMQ to handle alerts and fraud detection pipelines.
Collaborated with the security team to enforce strict data access policies and enable robust logging for audits.
Led implementation of Jenkins CI/CD pipelines for React and .NET builds, enabling daily deployments.
Developed internal tools for usage monitoring, saving 30+ hours/month of manual analysis.
Actively contributed to code review best practices and interview loops for hiring across Chicago tech teams.
Software Engineer (Volunteer) COVID Alliance
APR 2020 – JUN 2020: REMOTE
Developed privacy-first contact tracing dashboards in React for municipal health departments.
Integrated CDC and WHO data into backend services to power real-time regional statistics.
Implemented mapping features with Leaflet.js and GeoJSON to visualize local outbreak heatmaps.
Collaborated with a distributed team of engineers, epidemiologists, and civic technologists on a unified platform.
Focused on secure data protocols and informed consent to preserve user privacy. Software Engineer CME Group
SEP 2014 – APR 2019: CHICAGO, IL
Built Angular-based trading interfaces integrated with real-time data from WebSocket feeds and REST APIs.
3
Designed backend modules in .NET MVC and .NET Core for order routing, trade validation, and account summaries.
Worked closely with product teams on tools for derivative contract visualization and custom analytics.
Used Redis and PostgreSQL to optimize real-time order book synchronization and reduce latency.
Established test coverage with Selenium and xUnit, ensuring zero-defect deployments to trading environments.
Migrated legacy modules from Knockout.js to Angular 6+, improving code maintainability and performance.
Contributed to firmwide UI component library and accessibility standards initiative. TECHNICAL SKILLS
Frontend: React, Redux, TypeScript,
JavaScript (ES6+), HTML5, CSS3, Bootstrap,
Tailwind, Angular
Backend: C#, .NET6/8, ASP.NET Core,
RESTful APIs, Node.js, Express, Entity
Framework
Database: SQL Server, PostgreSQL,
MongoDB, Redis
Cloud & DevOps: AWS(Lambda, S3, RDS, API
Gateway), Azure DevOps, Docker,
Kubernetes, Jenkins, GitHub Actions
Testing: NUnit, xUnit, Moq, Jest,
Cypress, Selenium
Tools: Git, GitHub, Bitbucket, Jira,
Postman, Swagger, Figma
Methodologies: Agile, Scrum, Ci/CD,
TDD, Clean Architecture
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