Hi, I'm

Gerry Sihaj.

Full Stack Engineer.

I build software for real operational problems across government systems, research environments, and commercial projects — from requirements and architecture to production support.

Get in touchView projectsGitHub ↗

01 — About

A bit about me

I started working professionally in software engineering in 2019 while I was still a first-semester Informatics student. Since then, my work has moved across government-scale admission systems, commercial internal platforms, and medical imaging research.

I work across the stack with Go, Next.js, React, Laravel, Python, PostgreSQL, Docker, and Linux. The common thread is not the stack itself, but understanding the actual problem, designing maintainable systems, and staying close to delivery when complexity shows up.

I care about ownership: asking better questions, making tradeoffs visible, supporting systems in production, and helping teams get to a useful outcome without turning engineering into theater.

02 — Skills

How I deliver

Capabilities grouped by engineering responsibility, delivery ownership, and operational context.

Backend & architecture

APIs, business rules, refactoring, and maintainable data models for production systems.

  • Go
  • Laravel
  • REST
  • PostgreSQL
  • MySQL
  • Onion Architecture

Frontend workflows

React and Next.js interfaces for public services, admin panels, and operational workflows.

  • Next.js
  • React
  • TypeScript
  • Tailwind CSS

Research software

Visualization and exploratory tooling for medical imaging research collaborations.

  • Python
  • VTK
  • STL visualization
  • Medical imaging workflows

Delivery & operations

Deployment, monitoring, incident response, team coordination, and project delivery.

  • Docker
  • Linux
  • Nginx
  • Git
  • Production monitoring

03 — Projects

Selected work

Selected systems where the work involved requirements, implementation, coordination, and production responsibility.

01
Client project

PPDB Surabaya

Surabaya public school admission system

2020-2026

Problem

Public school admissions needed reliable online workflows for high-traffic registration, verification, and placement periods.

Government-scale admission system work spanning frontend development, Laravel backend development, architecture refactoring, production monitoring, incident response, and cross-team technical coordination.

Outcomes

  • Supported peak admission periods with around 3000 concurrent users
  • Improved backend maintainability through a large Onion Architecture refactor
  • Supervised backend SD and SMP teams during later project phases

Users

  • Applicants and families
  • School operators
  • City admission administrators

Modules

  • Registration workflows
  • Verification flows
  • Admission dashboards
  • Backend services
  • Laravel
  • React
  • PostgreSQL
  • Linux
Payroll slip generation employee setup screen
02
Client projectCompleted

Custom Payroll System

Tangga Mas Jaya Makmur

2023-2024

Problem

Hidden payroll rules and manual reconciliation made estimation difficult and exposed how much business discovery matters before implementation.

Led end-to-end delivery of an internal payroll platform under budget pressure — from proposal and requirement mining through client negotiation, team coordination, and full-stack implementation.

Outcomes

  • Delivered the system despite estimation and budgeting challenges
  • Managed a 4-developer team through unclear and evolving business rules
  • Completed the project without client complaints

Users

  • HR administrators
  • Finance team
  • Department managers

Modules

  • Attendance & shifts
  • Leave & overtime
  • Payroll components & tax
  • Role-based access
  • Laravel
  • React
  • MySQL
Warehouse work order product summary dashboard
03
Client projectIn production

Warehouse Management System

PT. Tomang Plastindo Utama

2025-Present

Problem

Inventory was tracked in disconnected sheets; inbound/outbound and bin locations were inconsistent across sites.

Led end-to-end delivery of a warehouse operations platform with a team of two developers and a network engineer — from schema design and workflow planning through Go API development, Next.js admin UI, deployment, and ongoing production support.

Outcomes

  • SKU-level visibility with bin and rack locations across sites
  • Approval-gated movements reduce posting errors in daily operations
  • Running successfully in production with ongoing rollout and support

Users

  • Warehouse operators
  • Inventory supervisors
  • Site managers

Modules

  • SKU & bin tracking
  • Inbound/outbound workflows
  • Approvals
  • Stock reconciliation
  • Go
  • Next.js
  • PostgreSQL
Delivery order creation and route assignment form
04
Client projectIn development

Delivery Tracking System

Armada Express

2025-Present

Problem

Dispatch and warehouse teams lacked a single view of stock movement and live delivery status across locations.

Leading end-to-end development of a logistics platform for stock management, item tracking, and live delivery reporting — from data model and architecture through active module delivery.

Outcomes

  • System architecture and data model defined for multi-warehouse operations
  • Core shipment tracking and stock movement modules in active development
  • Operational dashboards scoped for daily dispatch and warehouse review

Users

  • Dispatch coordinators
  • Drivers
  • Warehouse staff

Modules

  • Shipment tracking
  • Driver assignment
  • Stock movements
  • Operational dashboards
  • Go
  • Next.js
  • PostgreSQL
Blurred auto-generated organizational structure org chart preview
05
Client projectIn production

Job Analysis Platform

PT. Inti Optima Cemerlang (HR Consultant)

2026

Problem

HR consultants needed a structured platform to run job analysis workflows instead of relying on scattered documents and manual coordination.

Led the project end-to-end — from requirement gathering and solution brainstorming through system architecture, development, deployment, and production rollout. Built a platform to support HR job analysis processes and ensured successful adoption by the client's users.

Outcomes

  • Delivered full platform from requirements through production rollout
  • Client users adopted the system for ongoing job analysis work
  • Owned the full software lifecycle including post-launch support

Users

  • HR consultants
  • Client HR teams
  • Project stakeholders

Modules

  • Job analysis workflows
  • Automatic organizational structure
  • Reporting & documentation
  • User access management
  • Go
  • Next.js
  • PostgreSQL

04 — Research

Medical imaging research

Research collaborations focused on software engineering, visualization, and technical problem solving. These were research-scope projects, not clinical products deployed for patient treatment.

Medical imaging research systems

Research-scope software work supporting interdisciplinary discussions around anatomy, visualization, and planning workflows.

Areas

  • Jaw reconstruction planning
  • Custom titanium implant planning
  • Clear aligner software
  • Brain navigation systems

Contribution

  • Built Python tooling for STL and medical visualization workflows
  • Collaborated with researchers on technical feasibility and workflow design
  • Contributed to brainstorming around navigation accuracy and planning constraints
  • Python
  • VTK
  • STL
  • Medical imaging

Research outputs

Academic work completed alongside software engineering projects and medical imaging collaboration.

Areas

  • Completed a Master's Degree while handling engineering projects and research work
  • One conference publication as first author
  • One conference publication as second author

Contribution

  • Connected implementation details with research questions
  • Maintained clear boundaries between research prototypes and clinical deployment
  • Worked across software, visualization, and interdisciplinary technical discussions
  • Research collaboration
  • Technical writing
  • Prototyping

05 — Experience

Experience timeline

Professional work from early automation tasks to government-scale systems, research collaboration, and delivery ownership.

  1. Mobile Test Automation Intern · Ternaknesia

    2019

    Started professional software work while still a first-semester Informatics student.

    • Automated end-to-end testing for Flutter mobile applications
    • Used Flutter and Dart to establish a practical QA automation workflow
    • Learned to adapt quickly to unfamiliar technology and deliver useful results
    • Flutter
    • Dart
    • Test automation

  2. Frontend Developer · PPDB Surabaya

    2020

    Worked on React frontend development for public school admission workflows.

    • Built user-facing admission flow interfaces
    • Worked within a public-service context where reliability and clarity mattered
    • Coordinated frontend details with backend and workflow needs
    • React

  3. Backend Engineer · Simplus

    2020-2021

    Built and improved Laravel backend systems across APIs, deployment, payment integrations, and refactoring work.

    • Developed APIs and payment integration flows
    • Improved code quality by refactoring hard-to-maintain areas
    • Handled deployment tasks and production-oriented backend work
    • Laravel
    • API development
    • Deployment

  4. Backend Developer · PPDB Surabaya

    2021

    Worked on Laravel backend development and a large Onion Architecture refactor for the admission system.

    • Improved maintainability and code organization
    • Refactored core backend structure around clearer boundaries
    • Supported admission workflows from the backend side
    • Laravel
    • Onion Architecture

  5. Full Stack Engineer · PPDB Surabaya

    2022-2026

    Handled full-stack development, technical planning, production monitoring, and backend team supervision for peak admission periods.

    • Supported around 3000 concurrent users during peak periods
    • Participated in architecture, user-flow, and planning discussions
    • Supervised backend SD and SMP teams, mentored junior developers, and coordinated technical decisions
    • Laravel
    • React
    • PostgreSQL
    • Linux

  6. Research Software Collaborator · Medical Imaging Research

    2022-2026

    Contributed software engineering and visualization work for jaw reconstruction, clear aligner, implant planning, and brain navigation research.

    • Built Python and VTK tooling for STL visualization and planning workflows
    • Collaborated in technical discussions with interdisciplinary research teams
    • Kept the work clearly within research scope, not deployed directly for patient treatment
    • Python
    • VTK
    • STL visualization

  7. Project Manager & Full Stack Engineer · Tangga Mas Jaya Makmur

    2023-2024

    Delivered a custom payroll system while managing requirement discovery, client communication, negotiation, and a 4-developer team.

    • Created proposal materials and mined hidden payroll business rules through client meetings
    • Managed delivery pressure caused by underestimated business complexity
    • Completed the system without abandoning the project or leaving the client with unresolved delivery
    • Laravel
    • React
    • MySQL

  8. Full Stack Engineer (Contract) · PT. Tomang Plastindo Utama

    2025-Present

    Led end-to-end delivery of a warehouse management system with a team of two developers and a network engineer — from schema design and workflow planning through production deployment and ongoing support.

    • Led solution design for inbound/outbound workflows with approval gates
    • Owned schema, Go API, and Next.js admin UI; coordinated implementation with two developers and a network engineer
    • Running successfully in production with ongoing rollout and support
    • Go
    • Next.js
    • PostgreSQL

  9. Full Stack Engineer (Contract) · Armada Express

    2025-Present

    Leading end-to-end development of a delivery tracking platform with stock management, item tracking, and live reporting.

    • Owned solution design from requirements through active module delivery
    • Defined system architecture and data model for multi-warehouse operations
    • Building shipment tracking, stock movement, and operational dashboard modules
    • Go
    • Next.js
    • PostgreSQL

  10. Full Stack Engineer · PT. Inti Optima Cemerlang

    2026

    Led end-to-end delivery of a job analysis platform for HR consultants — from requirement gathering and architecture through deployment, production rollout, and user adoption.

    • Led requirement gathering, solution brainstorming, and system architecture
    • Owned backend, frontend, database design, deployment, and post-launch support
    • Ensured successful production rollout and adoption by client users
    • Go
    • Next.js
    • PostgreSQL

06 — Education

Education

ITS Surabaya — Master's and Bachelor's in Computer Science.

M.KomMaster's

Institut Teknologi Sepuluh Nopember (ITS)

Computer Science

Completed while handling software engineering projects and medical imaging research.

S.KomBachelor's

Institut Teknologi Sepuluh Nopember (ITS)

Computer Science

Completed in 2023; professional software work began in 2019 during the first semester.

07 — Contact

Let's build something

Tell me about your system — payroll, logistics, warehouse, or internal ops. I'll reply by email.

Available for contract and full-time roles

I typically reply within 1–2 business days

Email

gsihaj5@gmail.com
GitHubEmail