SinxLinonZ

About

[WIP]

Ziyi Lin

Software Engineer
Backend Systems · Full-Stack Web Development · Automation · Legacy Modernization

Based in Japan · Available for selected remote contract work

Profile

I am a software engineer based in Japan, focused on backend systems, full-stack web applications, internal tools, and engineering automation.

I enjoy working on products and systems that are difficult for more interesting reasons than simply needing more code: legacy systems with unclear behavior, operational workflows held together by manual work, production incidents, integration problems, and projects that need to become maintainable without stopping the business.

My work spans requirements clarification, architecture and implementation, testing, production support, and workflow improvement. I am comfortable taking ownership of a problem from investigation through delivery.

I work primarily with PHP, Laravel, Go, JavaScript, React, Next.js, MySQL, Redis, Linux, and Docker.

What I Do

  • Backend and API development
  • Full-stack web application development
  • Laravel and PHP system development
  • Go services and automation tooling
  • Legacy system analysis and modernization
  • Internal tools and operational workflow automation
  • Production incident investigation and remediation
  • Test automation, integration testing, and quality improvement
  • Developer workflow integrations using GitHub, Notion, webhooks, and serverless services

Experience

Software Engineer

OZVision Inc. · 2025–Present

Working on an in-house web product across backend development, product implementation, system maintenance, release preparation, and engineering workflow improvements.

  • Develop and maintain backend and full-stack features from requirements clarification through testing and release support.
  • Investigate complex production issues across web services, APIs, integrations, and platform-specific behavior.
  • Improve engineering workflows by connecting GitHub, Notion, webhooks, and serverless automation for ticket updates, delivery tracking, and lead-time visibility.
  • Support product delivery across system boundaries when necessary, including infrastructure, frontend, and mobile build or integration issues.
  • Use AI-assisted development pragmatically to accelerate implementation while preserving test coverage, code quality, and maintainability.

Independent Software Engineer

Japan · 2024–Present

Providing software development and modernization support for business systems in the mobility domain.

  • Maintain and extend internal business systems built with PHP, Laravel, JavaScript, Next.js, MySQL, Redis, Docker, Linux, and Node.js.
  • Investigated a production issue caused by a third-party API version change, identified the root cause within 30 minutes, and delivered a production fix within one hour.
  • Analyzed existing business logic, designed replacement functionality, implemented features, and performed unit, integration, system, and comparison testing.
  • Led quality-focused testing work for a system migration involving multiple engineers and test members.
  • Delivered an external-system integration involving detailed design, backend and frontend implementation, testing, and issue resolution.

Independent Software Engineer

Inventory Management System Rebuild & Security Investigation · 2023–2024

Delivered a complete rebuild of an inventory-management system while investigating security concerns in the legacy application.

  • Owned requirements gathering, infrastructure setup, system design, implementation, testing, deployment, and maintenance.
  • Reverse-engineered an existing Electron-based application after discovering suspicious collection and transmission of confidential client information.
  • Identified the affected communication flow, extracted evidence needed to determine the exposed information, isolated the transmission path, and supported remediation and reporting.
  • Worked with JavaScript, Electron, Node.js, Docker, Linux, and SQLite.

Software Engineer Contractor

Bit Tower Co., Ltd. · 2023
Cloud Migration & Legacy Batch Modernization

Worked on migration of a manufacturing infrastructure system to a cloud environment.

  • Analyzed legacy batch-processing logic and evaluated compatibility risks in the new environment.
  • Reimplemented and tested required batch components.
  • Completed analysis, implementation, and testing for a large legacy codebase within two weeks.
  • Technologies: Shell Script, Windows, MySQL.

Automation & Data Engineering Contractor

Ingester Co., Ltd. · 2022–2023
Speech Data Operations Platform

Built internal tooling for large-scale speech-data management and processing.

  • Developed automation tools for data organization, processing, and analysis workflows.
  • Reduced operational processing time by more than 80%.
  • Simplified repetitive procedures through Google API integrations.
  • Technologies: Go, JavaScript, Linux, Node.js.

Software Engineer Intern

FLUX Inc. · 2020–2022
Advertising Technology Platform

Worked on internal tools and operations automation for a publisher-focused advertising platform.

  • Generated and issued customer-specific JavaScript integrations while validating behavior on production websites.
  • Built internal tools and automation for repetitive operational work.
  • Identified manual bottlenecks, abstracted workflows, and reduced related operational effort by more than 50%.
  • Technologies: Python, JavaScript, Docker, Node.js, MongoDB.

Selected Technical Strengths

Backend Systems

PHP, Laravel, Go, REST APIs, background jobs, scheduled tasks, message queues, database design, production debugging, and legacy-system modernization.

Web Applications

JavaScript, React, Next.js, Vue.js, PHP, Laravel, responsive application interfaces, internal dashboards, and customer-facing product features.

Infrastructure & Data

Linux, Docker, Docker Compose, MySQL, MariaDB, Redis, SQLite, MongoDB, Nginx, Node.js, and development-environment setup.

Engineering Practice

System design, legacy analysis, requirements clarification, unit testing, integration testing, system testing, comparison testing, incident response, workflow automation, and maintainable code design.

Additional Experience

Java & Networking Instructor / Teaching Assistant

Tokyo University of Information Sciences · 2020–2025

  • Taught practical Java, networking, and network-programming sessions.
  • Designed discussion-based exercises and hands-on learning materials.
  • Supported students by connecting academic concepts with real-world software engineering practice.

University Network Operations Assistant

Tokyo University of Information Sciences · 2019–2023

  • Supported the construction, maintenance, and troubleshooting of campus network infrastructure.
  • Worked with Cisco networking equipment and Linux servers.
  • Investigated network incidents and supported network-environment renewal projects.

Education

Master’s Degree in Informatics

Tokyo University of Information Sciences · 2023–2025

Bachelor’s Degree in Information Systems

Tokyo University of Information Sciences · 2019–2023

Certifications

  • Cisco Certified Network Associate (CCNA), 2021
  • Japanese Class 1 Driver’s License, 2022

Languages

  • Chinese: Native
  • Japanese: Professional working proficiency
  • English: Professional technical communication

Availability

I am open to selected remote contract engagements, especially projects involving:

  • Backend or API development
  • Laravel, PHP, Go, JavaScript, React, or Next.js
  • Legacy-system modernization
  • Internal tools and workflow automation
  • System reliability and production issue investigation
  • Complex systems that need clearer architecture, better testing, or more maintainable operations

For consulting or contract inquiries, please contact me at [email protected].

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