Nikos Kougianos

Velocity RGS - Java

An audit-grade iGaming slot platform built as a deterministic Remote Gaming Server (Java 21, Spring Boot 3.x, Postgres & Redis), featuring:
- Server-authoritative spin outcomes with deterministic, bit-exact round replay from persisted RNG draws
- Idempotent mutations and session versioning to guarantee transactional integrity under retries
- Strict session FSM, BigDecimal money safety and in-memory JWT auth
- Three fully playable 20-payline slots with Free Spins, Power Bet, Bonus Buy and Pick & Collect features

Threedice: A dice betting game - Go

Full-stack application developed in Go, featuring:
- Idempotent Bet Placement
- Pessimistic Locking on Balance
- Transactional Integrity
- Integration Tests with Deterministic Dice

Spring Boot & Angular playground - Java/Angular

Full-stack Spring Boot and Angular application featuring:
- JWT-based authentication system with user management and role-based access control
- WebSocket integration for live chat functionality with user connection tracking
- External API integration (Disney API, DigitalOcean Status, UK Bank Holidays) with intelligent caching
- Kafka event streaming for cache analytics and audit trails
- MongoDB integration for persistent data storage with rate limiting and performance monitoring
- Advanced Redis caching with real-time analytics and cache-aside pattern implementation

Rest Api Aggregator - Java

Spring boot service with the following functionalities:
- Integrate with 3 REST APIs and dynamically combine the responses into 1, depending on the client's requested parameters
- Implement request throttling and batching of individual requests, using BlockingQueues.
- Create a scheduler that periodically checks items left in queues, and returns a response to the caller, guaranteeing a 10-second SLA

Carly Marketplace - Java

2 Spring Boot microservices powering a car marketplace, featuring:
- Role Based Access Control (RBAC) with Spring Security and an ADMIN > USER > FREE role hierarchy
- Persistence on a cloud MongoDB Atlas cluster (users, cars, roles & transactions)
- Asynchronous messaging via Apache Kafka on the cloud (Cloudkarafka)

Phonevice - PHP

This project offers a personalized smartphone recommendation based on 3 simple steps. Budget, features and types of use. An advanced recommendation algorithm takes place under the hood, that will always suggest the top 3 smartphones on the results page.

Data Science Thesis - Python

CLI application developed with Python, applying Supervised & Unsupervised ML Algorithms on a predefined dataset containing building energy features. The results from the algorithm executions are persisted on a cloud MongoDB cluster.

This project was developed in terms of my M.Sc. in Data Science.

Advanced Decision Making - Python

Python CLI application that applies Gaussian Naive Bayes and Multiple Linear Regression supervised algorithms and predicting with excellent accuracy student grades based on their social, family and other characteristics.