Software Engineer · St. John's, Newfoundland and Labrador

I build reliable backend systems and practical software products.

Computer Science graduate focused on Java, Spring Boot, APIs, event-driven architecture, cloud deployment, and maintainable engineering.

View selected work Resume GitHub LinkedIn

Open to software engineering, backend, cloud, QA automation, and technical analyst opportunities.

Hasan Rohan Tahsin

Backend systems · APIs · cloud-ready products

Current Direction

Focus: Backend systems, APIs, and cloud-ready product development
Core stack: Java · Spring Boot · Kafka · PostgreSQL · Flutter
Location: St. John's, Newfoundland and Labrador

Selected work

Projects with visible engineering decisions

A focused set of projects across backend systems, mobile product development, reliability planning, and Java desktop work.

In development

API

Events

Data

Ops

In developmentJava 21 · Spring Boot · Kafka

Event-Driven Order & Inventory Platform

A microservice-based commerce backend for coordinating order processing, inventory reservation, payment, shipping, and notifications.

Purpose

The project is focused on service boundaries, REST APIs, asynchronous Kafka workflows, PostgreSQL persistence, and a Docker-based local development environment.

Contribution

Defining service boundaries, API contracts, persistence models, and failure-handling paths while building the backend incrementally.

Models order, inventory, payment, shipping, and notification responsibilities as separate service concerns.
Uses Kafka event flows to keep long-running commerce operations asynchronous.
Includes inventory reservation and rollback concepts as part of the reliability design.

Java 21Spring BootKafkaPostgreSQLDockerREST APIs

Case Study

iFixIt mobile welcome screen with sign-in call to action.

iFixIt mobile login screen with email and password fields.

iFixIt mobile new ticket screen with issue details and attachment controls.

CompletedFlutter · Dart · Firebase Auth

iFixIt Ticketing App

A Flutter and Firebase service-ticketing application for customer requests, technician workflows, communication, and operational visibility.

Purpose

The application supports role-based request handling, real-time communication, offline drafts, feedback, and operational dashboard views.

Contribution

Led the team and contributed across product flow, Firebase-backed application behavior, and mobile implementation.

Led team delivery while coordinating customer, technician, and admin workflow requirements.
Implemented role-based routing, in-app chat, offline drafts, rating and feedback, and priority escalation.
Added analytics dashboard views and a time-prediction Cloud Function for service visibility.

FlutterDartFirebase AuthCloud FirestoreCloud Functions

Case Study

Planned

API

Events

Data

Ops

PlannedSpring Boot · REST APIs · PostgreSQL

API Monitoring & Incident Management Platform

A planned reliability platform for endpoint monitoring, uptime tracking, latency history, incidents, and service-level health.

Purpose

The planned system is intended to monitor public or internal API endpoints, retain status history, surface incidents, and support service-health review.

Contribution

Planning the API model, monitoring workflow, persistence shape, and reliability-focused product behavior.

Scope centers on scheduled endpoint checks, latency and status history, and incident timelines.
Design direction emphasizes practical service-level indicators rather than decorative dashboards.
Cloud deployment and alert rules are part of the roadmap, not represented as complete.

Spring BootREST APIsPostgreSQLScheduled ChecksCloud Deployment

FOUR board game main menu with New Game, Resume Game, Help, and Exit buttons.

FOUR board game player settings screen with player names, AI difficulty, and accessibility options.

CompletedJava · Swing · Desktop UI

FOUR Board Game

A Java Swing strategy game with a 9x9 board, multiple difficulty levels, save/load support, and computer-controlled gameplay.

Purpose

The project adds breadth through desktop Java UI work, game-state management, persistence, and turn-based computer gameplay.

Contribution

Built the game interface and gameplay behavior while managing state transitions and persistence support.

Implements a 9x9 board with multiple difficulty levels and computer-controlled turns.
Supports saving and loading game state for continued play.
Uses desktop UI patterns to make turn state, moves, and game progress visible.

JavaSwingDesktop UIGame StateFile Persistence

About

Current focus and background

I am a Computer Science graduate from Memorial University of Newfoundland with a minor in Business Administration. My recent work focuses on backend services, event-driven architecture, APIs, databases, and cloud-ready development.

I enjoy turning broad product requirements into structured systems: defining service boundaries, modeling data, handling failure cases, and building interfaces that people can understand. I am currently strengthening my Java, Spring, distributed-systems, cloud, and automation skills through hands-on projects.

Skills

Languages

JavaPythonJavaScriptTypeScriptDartSQL

Backend and APIs

Spring BootSpring CloudREST APIsKafkaFirebase Functions

Frontend and Mobile

ReactNext.jsFlutterTailwind CSS

Data and Storage

PostgreSQLMySQLMongoDBSQLiteFirestore

Cloud, DevOps, and Tooling

AWS fundamentalsDockerGitHub ActionsGitMavenVercelLinux fundamentals

Networking and Security

FortiGate administrationFirewall fundamentalsVPN fundamentalsRouting and switching fundamentals

Education

Memorial University of Newfoundland

Bachelor of Science in Computer Science

Minor in Business Administration

Completed December 2025 · St. John's, Newfoundland and Labrador

Certifications

FortiGate Administrator

Coursera

Firewall administration and network security operations.

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Enterprise Firewall Administration

Coursera

Firewall policy, inspection, and administration fundamentals.

View credential

Network Security Support Essentials

Coursera

Network troubleshooting, support workflows, and security operations fundamentals.

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Amazon Cloud Practitioner Essentials

Coursera

Covers AWS Cloud fundamentals: defining the AWS Cloud, differentiating on-premises, hybrid-cloud, and all-in cloud models, describing AWS global infrastructure, and explaining cloud benefits.

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HackerRank Software Engineer Certificate

HackerRank

Software engineering assessment credential.

View credential

Contact

Open to practical engineering work

I am interested in software engineering, backend, cloud, QA automation, and technical analyst opportunities. Reach out by email or connect with me on LinkedIn.

Email LinkedIn GitHub Resume