Engineering
How to build a private knowledge chatbot
A high-level architecture for building a private knowledge chatbot with Python, FastAPI, React, Supabase, retrieval, citations, model APIs, and a full implementation path.
I'm Dave, an AI engineer and founder of Datalumina. I lead AI projects for clients and teach developers how to build production systems with the same tools and workflows used in real engagements.
My work sits at the intersection of AI engineering, data systems, and freelance client delivery. Through Datalumina, I help developers move from tutorials to shipped projects, paid work, and stronger technical judgment.
The goal is practical education: clear concepts, working systems, and the business context needed to use AI skills in the real world.
What I've done
- 10M+ views across YouTube, LinkedIn, and courses
- Teaching a global community of 50k+ developers
- Building and scaling a 7-figure AI company
- Delivered 50+ custom B2B AI solutions
- Consulted for TimescaleDB, ClickUp, and n8n
- Helped 300+ developers launch freelance careers
- BSc + MSc in Artificial Intelligence (VU Amsterdam)
Posts by Dave
Career
How to build an AI SaaS: the service-to-software ladder
How to build an AI SaaS without external funding. Get paid to solve one company's painful problem, productize it for three to five similar customers, then go self-serve.
Engineering
How to protect your projects from supply chain attacks
Supply chain attacks hit axios, TanStack, and PyPI this year. Three package manager settings in uv and pnpm, exact version pins, a dependency cooldown, and locked installs, close the main attack paths.
Career
From data science to AI platform engineering
A transition guide for data scientists moving from notebooks and models to production AI systems with APIs, workers, evals, deployment, and ownership.
Career
How to become a freelance AI engineer
Learn how to become a freelance AI engineer by building practical AI projects, choosing a service offer, finding clients, pricing work, and moving toward long-term contracts.
Career
How to become a freelance machine learning engineer
A practical roadmap for machine learning engineers who want to freelance by deploying models, building ML APIs, improving evaluation, and finding client projects.
Career
How to become a freelance software developer
A practical guide for software developers who want to freelance, find first clients, scope projects, set rates, and build a sustainable technical client pipeline.
Career
How to become a freelance data scientist
A practical guide for data scientists who want to freelance, find first clients, package services, price projects, and turn analytical skills into paid client work.
Career
How to become a freelance data engineer
Learn how data engineers can start freelancing by packaging pipeline, warehouse, automation, data quality, and analytics infrastructure work into paid client projects.
Data
How to build hybrid search for RAG
Hybrid search for RAG combines BM25, dense embeddings, reciprocal rank fusion, reranking, and retrieval evaluation so your system retrieves better evidence.
Career
How to become a freelance data analyst
Learn how data analysts can start freelancing with dashboards, reporting automation, KPI cleanup, business analysis, and practical client acquisition strategies.
Data
How to build agentic RAG in pure Python
Build agentic RAG from scratch with three file tools that list, grep, and read. The same loop coding agents run, applied to your own knowledge, plus the production hardening that makes it hold up.
Career
How to become a freelance tech professional in 2026
A practical roadmap for developers, data professionals, and AI engineers who want to land freelance projects, set rates, write proposals, and build a client pipeline.
Career
Programming has changed: what I focus on now
How AI is changing software development, why companies are moving from AI-enabled to AI-first to AI-native, and the two skills I focus on as writing code gets faster and cheaper.
Career
The 5 skills that matter when AI writes the code
AI wrote every line of my two-week Rust rebuild. The five skills that kept me in control are systems thinking, full stack range, clear communication, ruthless simplification, and testing.
Infrastructure
How to build webhooks for your AI platform
Webhook architecture for production AI systems. Verify signatures, store events, enforce idempotency, dispatch async workers, and recover failures.
Engineering
How to build your own AI platform
A practical architecture for a personal AI platform with webhooks, scheduled workflows, agents, durable events, and a tiered context hub.
Workflows
How I think about a personal AI operating system
Why I'm building my personal AI operating system from first principles instead of cloning agent harnesses like OpenClaw, with three layers, a boring backend, and a context hub.
Career
How to deliver custom AI solutions for clients
The client AI delivery process behind 50+ custom B2B projects, covering discovery calls, proof of concept vs MVP scoping, two-week sprints priced at 10 to 20k euros, one standardized Python stack, and deployment on a Hetzner VM.
Workflows
The 5 levels of AI agents: from simple LLM calls to multi-agent systems
A working framework for the five levels of AI agent complexity, from augmented LLM calls and DAG workflows to agent harnesses and multi-agent orchestration, and how to pick the simplest level that solves the problem.
Workflows
How to build human-in-the-loop for AI agents
Practical human-in-the-loop for AI agents, covering two ways to halt a process in your Python backend, plus the SSE streaming and async production patterns that save state and resume after approval.
Workflows
Context engineering for AI agents: why they still fail in production
Context engineering for AI agents in practice, covering why bad context, not the model, causes most production failures, and how to fix system prompts, tools, and message history.
Engineering
How to build production AI systems
How to build production AI systems with APIs, retrieval, agents, evals, deployment, monitoring, and human review around the model.
Engineering
How to learn Python for AI in 2026
A three-phase roadmap to learn Python for AI in 2026, covering professional setup, the language core, and your first model API calls, plus how to use ChatGPT and Claude as a tutor instead of a copy machine.
Workflows
How AI agents actually work
An AI agent is an LLM call, a list of tools, and a loop. A walkthrough of a working coding agent in a little over 200 lines of Python, no framework required.
Engineering
How to set up LLM evals
A practical setup for LLM evals using raw events, unit tests, human review, LLM-as-a-judge, and A/B tests for production AI systems.
Workflows
How to build reliable AI agents
A field guide to reliable AI agents. Map the workflow first, use structured outputs for decisions, keep tool calling at the edges, and add recovery and human approval paths.
Data
How to prepare data for AI agents
Build an open-source pipeline that prepares documents, PDFs, and websites for AI agents, using Docling extraction, hybrid chunking, embeddings, and vector search in Python.
Data
How to implement hybrid search with PostgreSQL
A full walkthrough of hybrid search with PostgreSQL, combining semantic search through pgvectorscale, keyword search through full-text search and ts_rank_cd, and Cohere reranking on top, all in one database.
Data
How to build RAG with PostgreSQL
Build RAG with PostgreSQL using pgvector and pgvectorscale, keeping relational data and embeddings in one database, with similarity search, structured output, and advanced filtering.
Career
How to find freelance data and AI projects
A six-step roadmap for finding freelance data and AI projects, covering how to write a simple business plan, build your LinkedIn presence, sell solutions instead of skills, and land clients through the channels that actually work.
Data
PostgreSQL as a vector database: a beginner's guide to pgvector
PostgreSQL works as a vector database with the pgvector extension. A side-by-side speed test against Pinecone, the tables LangChain creates for you, and how to host it for free on Supabase.