Kim Justin Bustillo

Backend Developer

// Java · Spring Boot · AWS

profile

Backend-focused Software Engineer with hands-on experience building and maintaining Java Spring Boot applications in a production environment. Experienced in designing RESTful APIs, optimizing MySQL database performance, and co-leading legacy system migrations. Comfortable working across the stack when needed, with additional exposure to React frontends, AWS deployments, and workflow automation using n8n. Values clear, maintainable code and honest collaboration over individual ownership.

skills

Languages

Java SQL Python JavaScript HTML/CSS

Backend

Spring Boot Hibernate RESTful APIs

Database

MySQL Schema Design Query Optimization AWS RDS

Cloud & DevOps

AWS EC2 AWS S3 AWS App Runner Elastic Beanstalk Amazon SES Docker GitHub Actions Prometheus Grafana

Frontend

React Hooks Tailwind CSS

Automation

n8n Google Workspace

AI / Tools

AnythingLLM OpenAI API ComfyUI Prompt Engineering

experience

Data Analyst / Full Stack Developer

Paradigma International Inc. 2024 – 2025 Full Time · Hybrid
  • System Migration (Backend): Co-led the backend migration of a legacy platform to Spring Boot, building modular service layers and implementing DTO patterns to decouple API responses from database entities.
  • API Development: Designed and implemented RESTful APIs to support frontend requirements, managing data flow between the React client and MySQL database.
  • Labor Cost Analytics: Built backend modules to ingest payroll data, supporting real-time budget analysis and reporting for management decision-making.
  • CI/CD Pipeline: Owned the implementation of GitHub Actions pipelines to automate build and testing processes, reducing manual deployment errors for the team.
  • AWS Deployment: Managed application deployments to AWS Elastic Beanstalk for the main platform, and containerized deployments via Docker to App Runner for the AI chatbot service.
  • RAG Chatbot Integration: Forked and modified AnythingLLM to implement custom security controls, then containerized and deployed the modified build on AWS App Runner, integrated into the company's internal management system with session-based authentication.
  • Workflow Automation Prototype: Architected and demoed an n8n-based Google Workspace integration enabling chat-driven actions (e.g., creating work orders) with custom RBAC verification — shelved by management due to business scope decisions, not technical issues.

Junior Software Developer

Paradigma International Inc. 2023 – 2024 Internship · On-site
  • Resolved defects and implemented new features in legacy Java systems, improving application stability.
  • Optimized SQL database queries, reducing data retrieval times for critical application functions.
  • Collaborated with cross-functional teams on feature development and performance enhancement projects.

projects

Legacy System Modernization

Spring Boot · GitHub Actions · AWS · Prometheus

  • Contributed to refactoring a monolithic legacy codebase into modular Spring Boot services.
  • Diagnosed and resolved critical stability issues including circular dependencies and recursive data-layer calls.
  • CI/CD Pipeline: Built GitHub Actions workflows that compile and package the executable JAR using environment-specific secrets, upload to S3, and deploy to Elastic Beanstalk with rolling deployment via OIDC — replacing error-prone manual releases.
  • Email infrastructure: Set up Amazon SES for system notification emails and other transactional email services.
  • Monitoring: Deployed Prometheus and Grafana dashboards for application monitoring, supplemented with AWS CloudWatch alerts for infrastructure-level observability.
Spring Boot GitHub Actions AWS Elastic Beanstalk Amazon SES OIDC Prometheus Grafana

Internal AI Assistant

AnythingLLM (forked) · AWS App Runner · Spring Boot

  • Sole owner of a forked and modified AnythingLLM build, containerized and deployed on AWS App Runner, integrated into the company's internal management system (IMS).
  • Scoped to guidance only: No function calls — purpose-built to answer questions about company procedures, policies, and IMS navigation.
  • Backend modifications: Implemented workspace-scoped access levels and anonymized usage analytics for monitoring and usage analysis across the organization.
  • Content management: Built FAQ and articles sections within the IMS that automatically sync to the chatbot's vector store, keeping responses up to date with the latest company information.
  • Auth integration: Reads the signed-in user's IMS session and role permissions to dynamically control access to relevant knowledge bases.
AWS App Runner Spring Boot AnythingLLM RAG Vector Store

n8n Workspace Automation

n8n · OpenAI API · Google Workspace Bot

  • Built an AI agent on n8n using the OpenAI API with function calls to specific tools, deployed as a Google Workspace bot for management-level users.
  • Identity verification: Verified the user's Workspace domain and email against existing IMS account permissions and roles before executing privileged actions.
  • Shared the same company mascot persona as the IMS chatbot. Demoed successfully — shelved due to a business scope decision, not technical limitations.
OpenAI API n8n Google Workspace Function Calling

Generative AI Prototype

Python · ComfyUI · Virtual Try-On

  • Developed a Python backend integrated with ComfyUI for AI image processing, supporting a marketing campaign proof-of-concept.
  • Built a React frontend for file uploads and API polling against the Python backend.
  • ComfyUI Workflows: Created custom workflows for generating and modifying media assets used in social media promotions and advertising.
  • Validated technical feasibility for automating image enhancements for hospitality and tourism social media assets.
Python ComfyUI React

education

Bachelor of Science in Information Technology

Cavite State University

2020 – 2024

Hello!