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 exposure to React frontends, AWS deployments, CI/CD automation, and application monitoring with Prometheus and Grafana. 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 RDS AWS ECS AWS App Runner Elastic Beanstalk Amazon SES Docker GitHub Actions OIDC Deployments Prometheus Grafana AWS CloudWatch

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, defining service boundaries and module structure while building out the AWS deployment infrastructure in parallel as part of the same initiative.
  • API Development: Designed and standardized the full API layer across backend and frontend: built a centralized Axios middleware handling authentication, request validation, and error normalization, alongside a shared toast notification service, establishing a consistent implementation pattern for the team.
  • Labor Cost Analytics: Built backend modules to ingest and process payroll data, supporting real-time budget analysis and reporting for management decision-making.
  • CI/CD Pipeline: Owned the implementation of GitHub Actions pipelines: compiled and packaged the executable JAR, uploaded artifacts to S3, and deployed to Elastic Beanstalk via rolling deployment using OIDC, replacing error-prone manual releases.
  • AWS Deployment: Managed containerized application deployments to AWS ECS and Elastic Beanstalk using Docker, and deployed the internal AI chatbot service to AWS App Runner.
  • Monitoring and Observability: Deployed Prometheus and Grafana dashboards for application-level monitoring, supplemented with AWS CloudWatch alerts for infrastructure observability.
  • Email Infrastructure: Set up Amazon SES for transactional and system notification emails.
  • RAG Chatbot Integration: Forked and customized AnythingLLM, implementing workspace-scoped access control and anonymized usage analytics. Containerized and deployed the build on AWS App Runner, integrating it into the company's internal portal 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 hybrid RBAC and policy-based authorization, cross-referencing user roles and module-specific permissions against the main application database. Shelved by management due to business scope decisions, not technical limitations.

Junior Software Developer

Paradigma International Inc. 2023 – 2024 Internship · On-site
  • Debugged legacy Java Servlet/JSP modules including dynamic HTML rendering built with raw and generator functions, and resolved RedHat server configuration issues; extended the existing security package to enforce module-level access controls for UI navigation.
  • Optimized SQL database queries by implementing server-side pagination, selective field projection, and table-level caching to reduce unnecessary data retrieval on critical application functions.
  • Partnered with IT operations and product stakeholders on Work Order module delivery, aligning backend logic with internal workflow requirements.

projects & technical contributions

Legacy System Modernization

Spring Boot · GitHub Actions · AWS · Prometheus

  • Drove the refactoring of a monolithic legacy codebase into modular Spring Boot services, establishing and enforcing backend development standards and system design guidelines for the team including intern batches.
  • Identified and resolved architectural issues introduced during rapid feature development, including circular dependencies and recursive data-layer calls, maintaining system stability across concurrent workstreams.
  • Led enhanced security implementation across the refactored services.
  • Configured full CI/CD pipeline: GitHub Actions compiles and packages the JAR, uploads to S3, and deploys to Elastic Beanstalk via rolling deployment with OIDC, replacing manual releases.
Spring Boot GitHub Actions AWS Elastic Beanstalk Amazon SES OIDC Prometheus Grafana

Internal AI Assistant

AnythingLLM (forked) · AWS App Runner · Spring Boot

  • Owned end-to-end deployment, customization, and integration of a self-hosted AnythingLLM instance as the company's internal knowledge base chatbot.
  • Auth and access control: Integrated directly with the existing Spring Boot and React internal management system. Reads the signed-in user's session and enforces hybrid RBAC with module-level policy permissions to scope each user's accessible knowledge bases.
  • Content sync: Built FAQ and articles sections within the IMS that automatically sync to the chatbot's vector store, keeping responses current with the latest company information.
  • Security boundaries: Scoped strictly to information retrieval (RAG) with no function calls or privileged actions; those were isolated to a separate verified environment.
  • Analytics: Implemented anonymized usage analytics for monitoring adoption and usage patterns across the organization.
AWS App Runner Spring Boot AnythingLLM RAG Vector Store

n8n Workspace Automation

n8n · OpenAI API · Google Workspace Bot

  • Architected an AI-powered automation using n8n integrated with Google Workspace, enabling employees to trigger backend actions (e.g., creating work orders) through a chat interface via OpenAI function calling.
  • Hybrid authorization: Designed the workflow to extract the user's identity from chat context and cross-reference it against both role assignments and module-specific policy permissions in the main application database, ensuring only authorized users could trigger privileged actions.
  • Demoed successfully to stakeholders. Shelved due to a business scope decision: management wanted to preserve those capabilities exclusively within the paid management platform.
OpenAI API n8n Google Workspace Function Calling

Generative AI Prototype

Python · ComfyUI · Virtual Try-On

  • Built a proof-of-concept for an interactive art installation in Binondo, Manila aimed at increasing tourist foot traffic. Visitors scan a QR code on a banner stand, take a selfie on their own device, select an outfit, and receive an AI-generated try-on image.
  • Built a Python backend with ComfyUI handling image generation and a React frontend managing uploads and API polling for a loading indicator. No images or user data are retained after delivery to the client browser; only security logs are kept.
  • Built separate ComfyUI workflows for generating and modifying promotional media assets, reducing cost and turnaround time for social media and campaign materials.
  • Demoed the full pipeline to stakeholders confirming technical feasibility. Full deployment deferred due to competing project priorities at the time.
Python ComfyUI React

education

Bachelor of Science in Information Technology

Cavite State University

2020 – 2024

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