Nefeli Tavoulari

Web development:

• IAM API

  An Identity and Access Management API with single and multi-factor authentication (OTP/TOTP), role-based access control, session and device management, JWT with refresh tokens, email/sms verification, password reset and hashing, account lockout, profile management, and CAPTCHA-based bot protection.

  TypeScript - Twilio - Nodemailer - PostgreSQL - Redis

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• E-commerce API

  An e-commerce API implementing an order state machine, event-driven domain architecture, CQRS, RBAC, and external payment and shipping webhooks, with high-performance product and order management, advanced querying (filtering, sorting, pagination, search), pessimistic inventory locking, caching, audit logging, and comprehensive automated testing.

  Laravel - PostgreSQL - Redis - Nginx

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• Cloud-based Chat Application

  A chat application using microservice and event-driven architecture, deployed on AWS, using RDS Postgres, DocumentDB Mongo, AWS SQS, AWS SNS, MemoryDB Redis, AWS Lambda, DynamoDB, EC2, API Gateway, CloudWatch, in combination with DevOps best practices.

  Spring Boot - React - Typescript - Python - Jest - JUnit - Github Actions - AWS - Docker - Kubernetes - Websockets

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• Auctions Website

  An Ebay clone, featuring live messaging, OpenStreetMap implementation, a recommendation system, search, filters etc.

  React - NodeJS - Express - PostgreSQL - Docker - REST

Machine Learning - Deep Learning:

• Vaccine Sentiment Classifier

  A vaccine sentiment classifier using different machine and deep learning models. Logistic Regression, Feedforward Neural Network, LSTM, GRU, Bert pretrained model

  Python - PyTorch

Cybersecurity:

• Eclass Penetration Testing

  Penetration testing on a vulnerable version of eClass, using SQL injection, XSS, CSRF, RFI etc.

  PHP - MySQL

Low-level programming:

• Sniffer

  File scan and processing using inotifywait with interprocess communication, signals, pipes, named pipes, low level I/O.

  C - Bash - Makefile

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• TCP file transfer

  TCP file transfer simulation from a server to clients using sockets.

  C - Makefile

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• Inverted search engine

  Inverted search engine using bk trees, hash tables, multithreading.

  C++ - Bash - Makefile - Unit Testing - Github Actions

Compilers:

• LLVM translator

  An LLVM translator using visitor pattern, that performs static type checking and intermediate code generation.

  Java - JavaCC

Best Practices:

• Coding Best Practices

  A practical guide documenting the small things that make a big difference, covering code organization, testing, security, and performance, with lessons learned from the first years as a software engineer.

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• Software Architecture and Design Best Practices

  A comprehensive reference covering design principles (SOLID, KISS, DRY, YAGNI), 14 architecture patterns (microservices, event-driven, DDD, pub-sub and more), 25 design patterns across behavioral, creational and structural categories, and common anti-patterns to avoid, each with practical code examples and trade-off analysis.