# Alex Kim

**Email:** alex.kim@gmail.com | **Phone:** (415) 709-2843 | **LinkedIn:** linkedin.com/in/alexkim-dev | **GitHub:** github.com/alexkim

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## Professional Summary

Senior Backend Engineer with 6+ years of experience building high-throughput, fault-tolerant distributed systems in the fintech and payments domain. Currently processing 12M+ API calls/day at Plaid across payment and banking infrastructure with proven expertise in idempotent event processing, PCI-DSS compliance, and SLO-driven reliability engineering. Deep proficiency in Go, Python, and Java with hands-on experience in Kafka, PostgreSQL, Redis, and AWS at scale.

## Technical Skills

- **Languages:** Go, Python, Java, TypeScript
- **Databases & Storage:** PostgreSQL, Redis, DynamoDB, MongoDB
- **Event & Messaging Systems:** Apache Kafka, Amazon SQS
- **Infrastructure & Orchestration:** AWS (EC2, ECS, Lambda, SQS, S3), Docker, Kubernetes, Terraform
- **APIs & Protocols:** gRPC, GraphQL, RESTful API Design
- **Observability & Reliability:** Datadog, PagerDuty, Grafana, SLO-driven Development
- **Testing:** pytest, Locust (load testing), Integration & End-to-End Testing
- **Other:** CI/CD (GitHub Actions, Jenkins), Git, PCI-DSS Compliance

## Professional Experience

### Senior Software Engineer | Plaid | San Francisco, CA | Jan 2022 – Present

- Design and maintain core banking data aggregation and **payment processing services handling 12M+ API calls/day** in Go and Python
- Built **idempotent webhook delivery system** processing 3M+ events daily with at-least-once guarantees using SQS and DynamoDB — directly applicable to exactly-once payment processing semantics
- Led migration of monolithic Django application to **microservices architecture**, reducing deployment times from 45 min to 8 min
- Improved **P99 latency** of account linking flow from 1.8s to 620ms through database query optimization and Redis caching layer
- Collaborated with product and compliance teams to ship **PCI-DSS compliant transaction endpoints**, ensuring regulatory adherence for sensitive financial data
- **On-call rotation lead** for payments-core service maintaining 99.95% uptime SLA across mission-critical payment infrastructure
- Mentored 2 junior engineers through quarterly goal-setting, code reviews, and weekly 1:1s, contributing to team engineering culture
- Drove cross-functional **API design decisions** with product, partner engineering, and compliance stakeholders

### Software Engineer | Dropbox | San Francisco, CA | Aug 2019 – Dec 2021

- Developed **distributed file sync backend services** in Go supporting 500M+ stored files across distributed storage nodes
- Implemented **rate limiting and quota management system** that reduced abuse-related outages by 70% — relevant to payment platform abuse prevention
- Contributed to migration from legacy RPC framework to **gRPC**, improving inter-service latency by 30%
- Built internal CLI tool for **service scaffolding** adopted by 40+ engineering teams, improving developer experience and velocity
- Wrote comprehensive **integration and load tests** using pytest and Locust, catching 15+ production issues pre-deploy
- Participated in **architecture review board** for cross-team API standardization and design consistency

### Software Engineer Intern | Twilio | San Francisco, CA | Summer 2018

- Built real-time message routing service using Java and **Apache Kafka**, handling high-throughput event streaming
- Developed monitoring dashboards in Grafana tracking message throughput and error rates
- Achieved 92% code coverage through unit and integration tests for routing module

## Education

### B.S. Computer Science | University of California, Berkeley | 2019

- Relevant Coursework: Distributed Systems, Database Systems, Operating Systems, Algorithms
- Teaching Assistant for CS 162 (Operating Systems), Spring 2019

## Projects

- **kv-store** — Distributed key-value store in Go with **Raft consensus** for strong consistency guarantees (open source, 280+ GitHub stars)
- **api-bench** — HTTP API benchmarking tool in Rust, used internally at Plaid for **performance testing and capacity planning**

## Certifications

- AWS Solutions Architect – Associate (2023)