Open to AI/Data Science opportunities Thessaloniki, Greece

Gregory Barmpas

Data Scientist & AI Engineer building production-ready ML, RAG, and Generative AI systems.

I design and deploy machine learning, forecasting, retrieval, NLP, and LLM applications - from experimentation to scalable production APIs.

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AI systems portfolio
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RAG
Forecasting
LLM Apps
About

A practical AI engineer who can ship the model, API, and product surface.

Data Scientist / AI Engineer with 4+ years of experience developing machine learning, demand forecasting, predictive analytics, and Generative AI solutions. Experienced in statistical modeling, ensemble learning, time-series forecasting, NLP, LLM applications, RAG systems, and production AI systems. Strong background in Python, SQL, scikit-learn, PyTorch, FastAPI, cloud technologies, and end-to-end AI solution delivery.

4+ years experience

Generative AI & LLM applications

RAG / semantic search systems

Forecasting & predictive analytics

Production AI APIs

Python / SQL / FastAPI / cloud

Project Showcase

Recruiter-readable projects with real engineering depth.

Featured work prioritizes production AI systems, retrieval infrastructure, NLP internals, and full-stack deployment readiness.

GenAI

Loomi Brain

Featured

An AI knowledge/reasoning system focused on intelligent information retrieval, memory, and assistant-like workflows.

Explores how AI systems can retrieve, organize, and reason over information in assistant-like workflows.

Generative AIRAGAgentsLLMsMemory
1 0 0

Full-stack

Would You Rather App

Featured

A full-stack Next.js game with PostgreSQL-backed questions, voting, mode selection, Prisma migrations, seed/import tooling, and database-level duplicate prevention.

Provides an engaging question-based voting game with persistent data and scalable question management.

Next.jsTypeScriptPostgreSQLPrismaFull-stack
0 0 0

Retrieval

Custom Retrieval Pipeline with Reranker

Featured

End-to-end local retrieval pipeline with BM25, FAISS dense search, hybrid ranking, a custom scikit-learn feature reranker, evaluation metrics, CLI tooling, and Streamlit demo.

Improves document retrieval quality by combining sparse search, dense search, and learned reranking.

PythonBM25FAISSHybrid SearchReranking
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ML Infrastructure

Custom Vector Database

Featured

A lightweight educational vector database built from scratch in Python, featuring dense vector storage, metadata filtering, exact similarity search, graph-based approximate search, and JSON persistence.

Shows how vector databases work internally, including indexing, metadata filtering, and approximate search.

PythonVector DatabaseANN SearchSimilarity SearchMetadata Filtering
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NLP

Custom Embedding Model

Featured

Fine-tuning domain-adaptive Sentence-BERT embedding models for semantic search, retrieval, product search, support ticket matching, and job/CV matching.

Improves matching and retrieval quality by fine-tuning embeddings for specific domains and similarity tasks.

PythonSentence-BERTEmbeddingsSemantic SearchFine-tuning
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NLP

Custom BPE Tokenizer

Featured

Advanced tokenizer engineering project implementing BPE, byte-level BPE, WordPiece, and SentencePiece-style unigram tokenization, with benchmarking against Hugging Face tokenizers and API/demo tooling.

Explains and implements the core tokenization algorithms behind modern language models.

PythonNLPTokenizationBPEWordPiece
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What I Build

Business-facing AI systems with production constraints in mind.

Production RAG Systems

Systems that retrieve, rank, and generate grounded answers from private or domain-specific knowledge.

LLM-Powered Assistants

AI assistants for document processing, information retrieval, decision support, and workflow automation.

Forecasting & Predictive Analytics

Demand forecasting, backtesting, model monitoring, and predictive ML pipelines for business planning.

Custom ML/NLP Infrastructure

Embeddings, tokenizers, vector search, rerankers, APIs, and ML systems built from first principles.

Skills

A stack shaped around AI delivery, not just notebooks.

Machine Learning & Forecasting

PythonPandasNumPyscikit-learnXGBoostLightGBMStatistical ForecastingTime-Series AnalysisPredictive AnalyticsEnsemble LearningFeature EngineeringBacktesting

Deep Learning & NLP

PyTorchTensorFlowNeural NetworksNLPSentence-BERTEmbeddingsTokenizationSemantic Search

Generative AI

OpenAI APILangChainMCPRAGPrompt EngineeringAgentic AILLM ApplicationsAI AssistantsInformation RetrievalDocument Processing

Data & Databases

SQLMongoDBPostgreSQLVector DatabasesFAISSData Pipelines

Backend / MLOps / Cloud

FastAPIDockerKubernetesGitCI/CDAWSAPI DevelopmentCloud-native AI Systems

Frontend / Full-stack

Next.jsReactTypeScriptTailwind CSSPrismaVercel

Languages

Greek: Mother tongueEnglish: C2 Certificate of Proficiency
Experience

Machine learning, forecasting, and GenAI delivery across production teams.

Data Scientist

Deus Ex Machina

Sep 2025 - Current

  • Designed and deployed AI applications using OpenAI APIs, LangChain, FastAPI, and cloud-native architectures.
  • Built Retrieval-Augmented Generation systems using embeddings, vector databases, and semantic search.
  • Developed agentic workflows and AI assistants for information retrieval, document processing, and decision-support applications.
  • Implemented NLP pipelines combining LLMs, clustering, classification, information extraction, and semantic retrieval.
  • Collaborated with engineering teams to productionize AI solutions through APIs, containerization, and deployment workflows.
  • Evaluated LLM performance using structured testing, prompt optimization, and retrieval quality metrics.

Data Scientist

Dataviva

Nov 2022 - Oct 2024

  • Designed and optimized machine learning and statistical forecasting models for retail demand forecasting across large-scale product and store datasets.
  • Developed predictive analytics solutions using ensemble learning and feature engineering to improve forecast accuracy.
  • Built automated data pipelines for data preparation, model training, evaluation, forecasting, and reporting.
  • Conducted model validation, backtesting, error analysis, and performance monitoring for reliable production forecasts.
  • Led proof-of-concept initiatives and technical demonstrations for enterprise clients.
  • Collaborated with stakeholders to translate business requirements into scalable AI and analytics solutions.

Application Consultant / Engineer

Veltio

Oct 2021 - Nov 2022

  • Developed client-specific analytics and forecasting applications for supply chain optimization.
  • Collaborated with business stakeholders to define requirements and translate operational challenges into data-driven solutions.
  • Supported forecasting model implementation and deployment within customer environments.
  • Participated in solution design, validation, and performance evaluation processes.
Education

Computer science depth with data and web science focus.

MSc Data and Web Science

School of Informatics | Aristotle University of Thessaloniki

Oct 2021 - Sep 2024

Erasmus+ Computer Science / Software Engineering

Malardalen University

Jan 2021 - Jun 2021

BSc Computer Science

School of Informatics | Aristotle University of Thessaloniki

Sep 2017 - Sep 2021

Contact

Need AI systems shipped cleanly?

Reach out for Data Science, AI Engineering, LLM application, retrieval, or forecasting roles.