Summary
Overview
Work History
Education
Skills
Timeline
Generic

Alex Zhang

Sunnyvale,CA

Summary

Accomplished Backend Software Engineer with 8 years of professional experience specializing in microservices, distributed systems, and cloud-native architectures. At Walmart, optimized Kafka-based workflows with a 95% reduction in blocking time and led re-architecture initiatives, migrating monolithic applications to microservices. Proficient in Reactive Spring Boot, Java, Cassandra, Cosmos DB, Kubernetes, Prometheus, and Apache Spark, with hands-on experience across Azure and GCP. Strong problem-solving skills and expertise in delivering scalable, high-performance platforms in Agile environments.

Overview

7
7
years of professional experience

Work History

Senior Software Engineer

Walmart
Sunnyvale, CA
11.2023 - 09.2025
  • Led the modernization of a legacy monolithic architecture by designing and developing a scalable microservices-based platform, enabling better modularity, independent deployments, and maintainability. Integrated with over 30 Kafka topics, the new system handled more than 300 million events daily, significantly improving throughput.
  • Diagnosed and resolved critical bottlenecks in real-time event processing pipelines by redesigning the message handling logic and streamlining concurrency control. Reduced Kafka consumer lag by 100% and cut blocking time by 95%, ensuring real-time responsiveness for downstream services.
  • Designed a compensating event mechanism to handle failures and retries across distributed services. This eliminated silent message drops, improved end-to-end data reliability by 100%, and ensured transactional integrity across eventual-consistency-based workflows.
  • Improved observability and alerting by implementing real-time dashboards using Grafana and Prometheus, enabling better monitoring of service-level objectives (SLOs), alert fatigue reduction, and proactive incident detection.
  • Streamlined CI/CD pipelines for microservices deployed on Kubernetes clusters, using Docker containers and Helm charts. Enhanced release safety through canary deployments and reduced production rollout impact by 50% using node-affinity and readiness/liveness probes.
  • Leveraged Apache Spark for batch analytics jobs to identify outlier events and monitor traffic distribution across Kafka partitions. This reduced skew-related processing delays and enabled better capacity planning.
  • Participated in on-call rotations and responded to incidents by analyzing Prometheus metrics, Grafana dashboards, and Spark job logs. Resolved recurring system lag issues, cut down critical incident frequency, and improved mean-time-to-recovery (MTTR).

Software Engineer

PayPal
San Jose, CA
08.2021 - 05.2023
  • Worked as a backend java developer with SpringBoot Services and RESTFUL APIs.
  • Responsible for Design, Implement, Deliver exchange-currency APIs related new feature & enhancement.
  • Responsibilities: Integrated backend data services to expand available resources within software.
  • Gathered, defined and translated client requirements into product stories and actionable tasks.
  • Interpret business requirements and design exchange-currency related new features with applying frameworks like SPRING MVC, SPRING BOOT, messaging systems like Kafka etc.
  • Implement REST based Micorservices with using Spring Boot and Spring MVC, Spring transactions and Spring Security modules.
  • Decouple backend services using Rest template.
  • Using Kafka for stream processing, real-time data pipelines. Create a kafka producer to keep sending token to kafka cluster.
  • Write unit tests and perform operational support of applications with JUNIT, TESTNG, Mockito etc.
  • Build Java applications using Maven and deployed applications through application servers.
  • Debug and resolved functional test failures in pre-deploy phase of feature integration.
  • Maintain exchange-currency related services once they are in live by measuring and monitoring availability, latency, and overall system health.
  • Report status and manage risks within pricing related primary application/service.
  • Report any suspected information security violation or breach.
  • Tested and troubleshot application failure errors after new feature deployed to production and documented issue resolutions.
  • Delivered software solutions consistent with pricing product roadmap and meeting pricing release plan milestones.
  • Complete all periodic mandatory security trainings in accordance with Paypal's guidelines.

Java Developer

Mastercard
St Louis, MO
11.2018 - 07.2021
  • Worked as a full-stack java developer with Payments team.
  • Responsible for the development and maintenance of the payment processing systems and services related APIs which used to support the processing of electronic payments, including credit and debit card transactions, prepaid card transactions, and other payment-related micorservices.
  • Collaborating with other developers, designers, and stakeholders to understand the requirements and functional specifications of new features and systems.
  • Design, Developing and maintaining the server-side code and databases that make up payment backend systems.
  • Building and maintaining bill pay API by applying springboot framework, Spring MVC and web services that enable front-end systems to communicate with the backend systems.
  • Used Micorservice architecture with Springboot based services interacting through a combination of REST and Apache Kafka message brokers.
  • Implementing security and compliance measures to protect sensitive data and prevent fraud with OAUTH, JWT and HTTPS.
  • Write unit tests and assigned test jobs to team members and evaluated performance by applying test frameworks as Junit, TestNG, Mocking frameworks with mockito etc.
  • Monitoring and analyzing system performance and capacity, and making recommendations for improvements with ElasticSearch, Kibana.
  • Troubleshooting and resolving issues with the backend systems.
  • Participating in code reviews, testing and debugging of the systems.
  • Worked closely with other teams within Mastercard, such as the security team, Product team to ensure that the payment processing systems are secure and compliant with industry regulations.
  • Implemented Scrum-based Agile software development for analyzing, designing and developing applications.

Education

Master of Science - Computer Science & Information Systems

University of Washington
12-2020

Skills

Programming & Frameworks

Java, Spring Boot (Reactive), Microservices, RESTful APIs, Functional & Reactive Programming

Event-Driven & Messaging
Apache Kafka, Event Processing, Stream Processing, Pub/Sub

Databases
Cassandra, Cosmos DB, PostgreSQL, MySQL, Redis

Cloud Platforms
Microsoft Azure, Google Cloud Platform (GCP), Kubernetes, Docker

Big Data & Analytics
Apache Spark, Hadoop Ecosystem, Data Pipelines, Batch & Real-Time Processing

Monitoring & Observability
Prometheus, Grafana, ELK Stack, Logging & Metrics

Software Engineering Practices
Agile/Scrum, CI/CD (Jenkins, GitLab CI), Test-Driven Development (JUnit, Mockito)

Timeline

Senior Software Engineer

Walmart
11.2023 - 09.2025

Software Engineer

PayPal
08.2021 - 05.2023

Java Developer

Mastercard
11.2018 - 07.2021

Master of Science - Computer Science & Information Systems

University of Washington

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