Senior AI Specialist | NexGen
NVIDIA GTC
As a Senior AI Specialist at NexGen Cloud, I had the privilege of presenting our work on Large Language Models (LLMs) and GPU optimization at one of the world's largest AI conferences.
Credentials
Highlighted projects
Director of AI | NexGen Cloud
Hyperstack AI Studio
Led the development and implementation of an end-to-end Generative AI platform for building, fine-tuning, and deploying custom AI models.
More work
Freelance Gen AI Specialist
AI Grocery Agent
Built a personal AI agent that does my groceries: I chat with it via WhatsApp or Telegram and it fills the basket for me using MCP tools.
Senior AI Specialist | NexGen
LLM deployment tutorials
Wrote dozens of technical articles for Hyperstack on deploying LLMs like DeepSeek, Llama, and Qwen on GPU infrastructure.
Freelance Python Developer
Programming tutor
Contributed to a coding bootcamp (Status200) designed for students with a migration background to build tech skills and transition into tech careers.
Freelance Gen AI Specialist
Gen AI Model Trends
Wrote a Medium article on the latest Gen AI model trends in December 2025: MoE models, quantiziation, and long context windows
Freelance Gen AI Specialist
Fine-tune LLMs tutorial
Wrote a comprehensive tutorial on Medium about fine-tuning an LLM, from data generation to hosting a chatbot online.
Freelance Gen AI Specialist
Evaluating LLMs
Wrote a comprehensive tutorial on Medium about evaluation LLMs, from including theory and practical application.
Freelance Gen AI Specialist
Large Language Models
Deployed open-source Large Language Models on AWS Sagemaker and improved outputs with Retrieval Augmented Generation (RAG) techniques.
Freelance Gen AI Specialist
Common LLM mistakes
Wrote a Medium article on common mistakes in local LLM deployment with specific solutions and examples using Ollama
Senior AI Specialist | NexGen
LLM Inference Toolkit
Developed an open-source LLM Inference Toolkit designed to kick-start your LLM projects in the cloud.
Senior AI Specialist | NexGen
GPU Selector for LLMs
Developed a handy tool to quickly calculate the GPU memory requirements for LLM use cases (e.g. inference, finetuning).
Freelance Data Scientist
Digital Nomad Conference
Spoke at the De Rantau Nomad Conference in Langkawi about working remotely from Kuala Lumpur with Malaysia's Digital Nomad Visa.
Freelance Gen AI Specialist
Gen AI & Recruitment
Developed a Generative AI & Process Mining solution that automates recruitment tasks using advanced models like Large Language Models.
Senior Data Scientist | Valcon
AI Competitive Pricing
Developed a competitive pricing solution using state-of-the-art AI techniques like transformer models and deep neural networks.
Data Scientist | Deloitte
Cognitive Deforestation
Contributed to a Cognitive Deforestation project predicting deforestation risks using contextual geographical data.
Freelance Data Scientist
Serverless LLM
Wrote a Medium article on quick and cheap deployment of open-source LLMs with serverless services on AWS.
Freelance Gen AI Specialist
Gen AI - Coding Game
Created a web-based programming game using React and AWS, enhanced with ChatGPT-generated questions to challenge coding skills.
Freelance Gen AI Specialist
Gen AI - Streamlit
Developed a tool for building ML and Data Science web apps, using OpenAI's ChatGPT to eliminate constant code copying between browser and IDE.
MSc Data Science & Business
Security congress talk
Spoke at a security congress about my award-winning research on detecting mobile malware with machine learning.
MSc Data Science & Business
Academic publication
Published a paper in ACM Digital Threats: Research and Practice (DTRAP) titled “Dynamic Detection of Mobile Malware Using Smartphone Data and Machine Learning”.
MSc Data Science & Business
JBISA Thesis award
Received the Joop Bautz Information Security Award 2018 for the best Cybersecurity master thesis in the Netherlands.
Demos & apps
Real, working deployments and apps I’ve built. Try them yourself.
Hands-on explainer
Claude Watermark Playground
An interactive explainer of SynthID-style text watermarking: regenerate a sentence word by word and watch a secret key tip each choice.
macOS app
Powerspaces
A macOS app that makes Spaces behave like Windows virtual desktops, with a per-desktop dock and smart launch. Designed, built, and shipped in days with Claude.
Live demo
Lex Llama
Chat with a Llama fine-tuned end to end: synthetic data generation, LoRA training, and deployment. The working result of my fine-tuning tutorial.
Live demo
Code Game
Coding challenges with ChatGPT as your sidekick. A period piece: built months after ChatGPT launched, when wiring an LLM into a product was still a radical idea.
Reviews
★★★★★
Sebastian was extremely knowledgable, detailed and fast in his work. He integrated very well with the team and was able to help achieve a practical, cost effective solution to a large scale task [..] Highly recommend!
★★★★★
Sebastian was very knowledgable in Large Language Models / AI. He was extremely professional, quick [..] and his communication was very impressive. He’ll be our “go to” “LLM / AI guy” from now on.
★★★★★
[Sebastian] demonstrated professionalism, dedication, and put in significant effort to deliver quality work [and was] attentive to details and showed a strong understanding of the task at hand [..]
★★★★★
Sebastian is a[n] A+ worker who is smart, extremely detailed and quick to respond. Highly recommend. Will work with us on many future projects!
★★★★★
Sebastian was excellent to work with, he understood our requirements and went above [and] beyond in his delivery
★★★★★
Great work! [Sebastian] solved a very difficult problem quickly and efficiently. Would hire again!
★★★★★
Sebastian is a great freelancer and was key to the success of this project
★★★★★
It was a pleasure to work with Sebastian! He did help us a lot!
★★★★★
Awesome work! Will 100% hire again
Tools & technology
AI & GenAI
- Generative AI
- Large Language Models
- Natural Language Processing
- Computer Vision
ML & Delivery
- Machine Learning
- MLOps
- Forecasting & Predictive Analytics
- CI/CD
Cloud & Platforms
- Azure
- Google Cloud
- AWS
- Databricks
Models & Methods
- Transformers
- Neural Networks
- XGBoost
- Random Forest
- Regression Analysis
- SARIMA
Languages
- Python
- JavaScript
- Java
- R
Frameworks & Libraries
- PyTorch
- TensorFlow
- Scikit-learn
- LangChain
- OpenAI API
- PySpark
- spaCy
- NLTK
- OpenCV
- YOLO