Senior Software Engineer, Python & React

Jonathan Barbalas

Chicago, IL • ********.********@*******.*** • 315-***-**** • www.linkedin.com/in/jonathan-barbalas-3492a15a SUMMARY

Software Engineer with 13 years of experience, most recently at Instacart, where the team builds the retailer storefront and order fulfillment platform used by millions of customers shopping for groceries online. At Eversight, built Python pricing and promotion tools that helped retailers run data-driven experiments at scale. Cut API response times from roughly 2.5 seconds to 800 milliseconds through PostgreSQL query optimization and Redis caching, and reduced page load times from 3.2 seconds to 1.1 seconds with React performance work. Holds a B.S. in Computer Science from Wheaton College. SKILLS

Languages & Frameworks: Python, FastAPI, Java, Spring Boot, React.js, TypeScript, REST APIs Data & Messaging: PostgreSQL, Redis, Kafka, SQL, data pipelines Cloud & Infrastructure: AWS (EC2, S3, RDS, Route 53), Docker, Kubernetes Testing & CI/CD: PyTest, GitHub Actions, Jenkins, automated testing Practices & Collaboration: Agile/Scrum, microservices architecture, on-call rotations, cross-functional teams

EXPERIENCE

Software Engineer Instacart 09/2022 – Present

Built and enhanced backend microservices using Python and FastAPI for product catalog, inventory, pricing, checkout, and order management workflows serving millions of customers across retailer storefronts.

Improved API response times from roughly 2.5 seconds to 800 milliseconds through PostgreSQL query optimization, Redis caching, and asynchronous processing, making product search and cart operations noticeably faster for shoppers.

Reduced storefront page load times from 3.2 seconds to 1.1 seconds by implementing React code splitting, lazy loading, and frontend performance enhancements that kept users engaged during peak traffic.

Designed and maintained 40+ REST API endpoints serving product search, cart, pricing, inventory, and order tracking functionality across customer-facing and internal tools. Developed Kafka-based event processing services supporting inventory updates, order status changes, and notification workflows so shoppers and delivery partners see accurate order state in real time.

Automated deployments using Docker, Kubernetes, and GitHub Actions, cutting release time from 30 minutes to under 10 minutes so the team could ship weekly without lengthy hand-offs. Supported 10+ production microservices and participated in on-call rotations contributing to 99.9% service availability for customers relying on same-day grocery delivery. Software Engineer Eversight 10/2020 – 09/2022

Developed Python and FastAPI microservices supporting pricing experiments, promotion configuration, analytics processing, and retailer integrations for consumer brands running large-scale pricing tests.

Reduced analytics dashboard load times from roughly 4.5 seconds to 1.4 seconds by optimizing PostgreSQL queries, API aggregation logic, and frontend rendering so pricing analysts could act on experiment results faster.

Improved API response times from 2.2 seconds to 700 milliseconds through Redis caching, database indexing, and asynchronous request processing that cut wait time during high-volume reporting periods.

Cut reporting query execution against large transactional datasets from 8–12 seconds to under 2 seconds, reducing the time pricing teams spent waiting for promotional performance reports. Increased automated test coverage from 60% to 85% using PyTest and CI/CD pipelines, catching regressions before they reached production so the team shipped with more confidence. Reduced deployment times from 20 minutes to under 7 minutes using Docker, Kubernetes, and GitHub Actions so new pricing features reached customers without long release cycles. Sr Software Engineer Capital One 04/2019 – 10/2020 Developed Java and Spring Boot microservices supporting customer-facing digital banking and account-servicing functionality for millions of customers managing their finances online. Contributed to modernization of customer-facing applications as Capital One migrated workloads from on-premises data centers to AWS, moving production traffic through phased releases from 1% up to multi-region architecture.

Implemented event-driven processing for account activity and application workflows using Kafka streaming, supporting real-time updates as customers interacted with their accounts.

(Volunteer) Sr Data Engineer COVID Alliance 04/2020 – 07/2020 Built data pipelines for COVID-19 resource tracking and aggregation using Python, with automated workflows handling data from multiple sources during the early pandemic response. Software Engineer CME Group 08/2016 – 04/2019

Developed backend services supporting trading platform operations using Python, working in a high- availability environment where system reliability directly affected financial markets. Built and maintained REST APIs for market data and trading operations, handling real-time market information for trading firms and exchanges.

Implemented data streaming with Kafka for real-time market data delivery, ensuring low-latency updates reached trading systems during market hours. Improved system reliability through database optimization and caching strategies that kept trading platforms stable during peak volume periods.

Collaborated with trading desk teams to deliver features supporting trading operations, gathering requirements and shipping updates in two-week sprints. Software Engineer First National Bank of America 09/2014 – 08/2016 Developed backend services using Java for banking operations and customer-facing functionality, supporting core account management and transaction processing workflows. Designed and maintained APIs for account management and transaction processing, working with SQL databases to ensure data integrity across banking systems. Undergraduate Research Assistant Wheaton College 05/2013 – 07/2014 Developed data analysis and visualization tools for academic research projects, building foundational programming skills in Python and statistical methods. Assisted with research data processing and validation, contributing to published findings in the computer science department.

EDUCATION

Wheaton College 08/2010 – 05/2014

Bachelor of Science, Computer Science

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