songjaehyun

About

Backend-focused software engineer
building reliable systems.

Software engineer with experience designing backend services, leading enterprise platform migrations, and building systems that prioritize reliability, clarity, and long-term maintainability.

My work spans backend architecture, cloud delivery, caching strategy, and full-stack implementation. I enjoy building systems where correctness, performance, and developer clarity matter.

Through DontSweat.Tech, I also design and deliver client and product work including Vye Coconut Water, Farero, and Jumun—moving between product decisions, application code, infrastructure, and launch operations as needed.

Backend

Java, concurrency, REST APIs, SQL, Spring Boot, JVM fundamentals, caching strategies, stateful backend services.

Platform

Docker, Linux, CI/CD pipelines, distributed deployment, Apache HTTP Server, CDN caching and invalidation strategies.

Frontend

React, TypeScript, JavaScript (ES6+), HTML, CSS, accessibility, web performance, developer-facing UI.

Experience

Independent Software Engineer

DontSweat.Tech

Design and deliver client software across ecommerce, SaaS, wholesale operations, architecture, and cloud infrastructure.

Built Vye's commerce experience and launch infrastructure, while developing Farero's workforce coordination workflows and Jumun's independently deployable storefront, admin, and Spring Boot API.

Own the path from unclear requirements through implementation, rollout planning, production readiness, and maintainable handoff.

Software Engineer

PiSrc — New York

Built and maintained Java-based backend services supporting correctness-sensitive workflows, cache consistency, and user-specific state across authentication and session transitions.

Led migration of enterprise platform infrastructure from on-premise deployment to a cloud-native architecture, refactoring over 40 backend services while preserving transactional integrity and zero-downtime releases.

Designed multi-layer caching and invalidation strategies across Apache, Dispatcher, and CDN layers to reduce origin load and improve global response latency.

Served as a technical lead for enterprise clients, translating product requirements into backend architecture, frontend implementation, and infrastructure decisions while remaining hands-on in development and production support.

Partnered with security and QA teams to remediate critical vulnerabilities through safer serialization patterns, stricter validation, and hardened runtime configurations.

Technical Instructor

App Academy — New York

Taught JavaScript fundamentals and software engineering concepts to aspiring developers preparing for selective coding bootcamps. Provided code reviews, debugging guidance, and mentorship focused on algorithmic thinking and clean coding practices.

Technical Writer

Croud — Freelance

Authored technical documentation for NoSQL databases in collaboration with international editorial teams, focusing on clear explanations of complex technical concepts and developer-facing documentation.

Engineering principles

Clear systems

Systems should be easy to reason about. I value strong service boundaries and architecture that remains understandable as it evolves.

Reliability first

Correctness and predictability matter. I prioritize designs that behave deterministically and handle failure modes gracefully.

Practical engineering

Architecture should serve the product. I favor pragmatic systems that balance design quality with real operational constraints.

About this site

This portfolio is intentionally static and lightweight. It presents my work without runtime APIs, application accounts, or backend dependencies.

The goal is simple: make the scope of my engineering work clear and let the products, delivery decisions, and outcomes speak for themselves.

Connect

If you'd like to see more of my work or connect professionally, you can find me through the following channels.