Portfolio

Josef Stein Butzke

Software Engineer

📍 Yokohama, Japan📞 070-9091-6757📧 josef-stein@hotmail.comLinkedInGitHub

I love algorithms and new computation knowledge that guided me to study more and discover new ways to use coding — mobile apps, servers, games, IoT, data analysis, and more. My favorites are mobile apps and games because we can see our users literally touching our creations. I'm always looking to increase code performance and UX.

Skills & Certifications

Languages

JavaScript (6 yrs), C# (2 yrs), C (1 yr)

Frameworks

React Native, Next.js, Node.js, React, Unity, Prisma, GraphQL

Databases

Postgres, MySQL, MongoDB

Cloud

AWS, Digital Ocean

Tools

Git, JIRA, Figma, Docker, Insomnia

Methodology

Domain Driven Design, Clean Code, SOLID

Human Languages

English (Business), Japanese (N3), Portuguese (Native)

Certifications

JLPT N4 — studying N3

Work Experience

Software Engineer · Travelience · Tokyo, Japan
Mar 2023 — Present
  • ·Implemented new features: Airport Transfer, ChatGPT app, UI Revamp
  • ·Improved system code security and maintainability
  • ·Increased SEO and overall system performance
  • ·Reduced infrastructure costs
  • ·Trained new team members

Key Achievements

  • ✦Designed and implemented a new photo gallery with collage style
  • ✦Improved main search feature from ~3000ms to <100ms using pre-calculated columns and caching
  • ✦Reduced bad/low-quality links from 45% to 15% (LCP/CLS improvements)
  • ✦Led library upgrades to latest versions
  • ✦Built a new modal UI with fluid mobile/web animations
  • ✦Replaced spinner loading with shimmer clone effect
  • ✦Achieved SEO score of 100 on all public pages; boosted performance by 30%+
  • ✦Sped up the test pipeline by ~25%
Lead Software Engineer · Zazuu Startup · ES, Brazil
May 2020 — Feb 2023
  • ·Collaborated with stakeholders to plan sprints and features
  • ·Managed deployments across server, mobile apps, and websites
  • ·Defined code architecture with SOLID principles and unit tests
  • ·Trained new engineers

Key Achievements

  • ✦Designed system architecture and reusable web components
  • ✦Built a complex cart system handling multiple product types, discounts, coupons, and combos
  • ✦Implemented a referral system
  • ✦Built financial reports and appointment management system
  • ✦System supported 1,000+ orders per month
Internship · Court of Auditors of Espírito Santo · ES, Brazil
May 2020 — Feb 2023
  • ·Strong focus on React Native, Node.js, and databases
  • ·Collaborated with stakeholders on sprint planning
  • ·Managed full-stack deployments
  • ·Built system architecture and web components

Personal Projects

Greenhouse Automation

React Native · Arduino · Bluetooth · SQLite

Mobile app to control a Bluetooth Arduino managing irrigation and ventilation of a mini greenhouse based on soil moisture, temperature, and humidity. Data is stored offline in SQLite and visualized in graphs.

In The Dolmen

Unity · C# · Procedural Generation

A 3D game featuring procedural terrain with Perlin noise, procedural animations, and original 3D modeling. An ongoing project exploring storytelling, visual effects, and game design.

Education

Bachelor's Degree, Computer Science

University VilaVelha — Brazil, 2015–2020

Soft Skills

do not click