RAG vs Fine-Tuning
Know When to Use Each.

The wrong choice costs months and thousands in compute.
Learn the decision framework that senior AI engineers use.

Choosing Wrong Costs You Big.

Unclear decision criteria. Blog posts contradict each other, leaving you guessing which approach fits your use case.

Cost and complexity tradeoffs are murky. Fine-tuning seems powerful but RAG seems simpler. Which actually saves money?

Wrong approach wastes months. You build a RAG system that needed fine-tuning, or fine-tune when RAG would've worked better.

A Clear Decision Framework.

The World-Class AI Engineer Cohort

RAG and fine-tuning solve different problems. RAG excels at injecting external knowledge; fine-tuning excels at changing model behavior. Once you understand this distinction, the right choice becomes obvious for most use cases.

1

Understand the Core Difference

Knowledge injection vs behavior modification

2

Map Your Use Case

What problem are you actually solving

3

Apply the Decision Framework

Choose with confidence, not guesswork

Meet Your Mentor

Zen van Riel

My aim has been the same for years: become a world-class AI engineer. Every career move I've made has been measured against that.

I started as a software tester on a $500/month internship in the Netherlands. Taught myself to code, learned to ship real systems, and worked my way to Senior Engineer at GitHub.

Then I left GitHub. I joined an AI research lab as Member of Technical Staff, where I currently build products for secure AI monitoring.

The cohort draws directly from my real experience so you can make progress fast.

I run this special cohort with only a few people because hands-on work with me is what it takes to bring you to become a world-class AI engineer.

Career progression from Intern to Senior Engineer

Real Results

Vittor

Vittor

AI Engineer

Built and deployed his portfolio piece, then landed the AI role

"The coaching played a huge part in my success. I focused on AI fundamentals, the certification path, and soft skills like professional writing. Having access to expert guidance gave me confidence during interviews and helped me feel I was on the right path.

I built my own platform (simple but functional) and deployed it on AWS. I used it in my portfolio and showcased it during interviews. The way complex topics were explained, especially the restaurant analogy for AI systems, really stuck with me. Focusing on doing the basics well was absolutely essential."

What You Will Get

8 Weekly Tuesday Sessions

3 hours each for 24 live hours total.

Project Scoping at Kickoff

We set the scope of what you'll ship and the milestones to get there before the live sessions start.

Code Reviews

Reviews of your code from Zen during the cohort.

Lifetime Demo Access

Every architecture demo is recorded and yours to keep.

Demo Day

You present what you built and get feedback from Zen, with a recording you can use in your portfolio.

12 Months Community Access

Included with the cohort.

Every Week You Hesitate Is a Week Building the Wrong Thing

8
Weeks
6
Seats per Cohort
24
Live Hours with Zen

Frequently Asked Questions

What's the difference between RAG and fine-tuning in simple terms?

RAG (Retrieval-Augmented Generation) gives the model access to external documents at query time. It's like giving someone a reference book to look things up. Fine-tuning changes the model's weights through additional training. It's like teaching someone new skills they'll remember forever. RAG adds knowledge; fine-tuning changes behavior.

When should I use RAG over fine-tuning?

Use RAG when: 1) Your knowledge base changes frequently and you need up-to-date information, 2) You need citations and source attribution, 3) You're working with proprietary documents the model was never trained on, 4) You want to avoid the cost and complexity of training. RAG is ideal for Q&A over company docs, customer support bots, and research assistants.

When should I use fine-tuning over RAG?

Use fine-tuning when: 1) You need consistent style, tone, or formatting the base model doesn't naturally produce, 2) You're teaching domain-specific reasoning or classification patterns, 3) You need faster inference without retrieval latency, 4) The knowledge is relatively static and doesn't need frequent updates. Fine-tuning excels at specialized classification, consistent brand voice, and domain-specific reasoning.

Can I combine RAG and fine-tuning?

Yes, and this is often the best approach for complex applications. Fine-tune for behavior (style, reasoning patterns, output format) and use RAG for dynamic knowledge. For example, fine-tune a model to respond in your brand voice and follow your output schema, then use RAG to inject product information and customer context at query time.

Which is more cost-effective: RAG or fine-tuning?

It depends on scale and use case. RAG has higher per-query costs (embedding + retrieval + longer prompts) but zero training costs. Fine-tuning has upfront training costs but lower per-query costs and no retrieval infrastructure. For low-volume applications, RAG is usually cheaper. At high scale with stable requirements, fine-tuning often wins. The real cost is building the wrong thing first.

How can coaching help me make better AI architecture decisions?

The cohort gives you a senior AI engineer's perspective on your specific use case. Instead of reading generic blog posts, you get direct guidance: 'For your customer support bot with 50K monthly queries and frequently changing product info, here's exactly what I'd build.' You skip the trial-and-error phase that costs most teams months of wasted effort.

I've signed up for cohorts before and dropped out. How is this different?

It probably isn't, and you should hold the money. Most cohort dropouts are people who couldn't articulate what they were shipping when they signed up. That's why the consult exists, and why I turn down most applications. If we get on the call and you can't tell me what you'll have shipped at the end of week 8, I'll point you to the AI Native Engineer community until you can.

I'm not pivoting careers. I want to build a product. Does this still work?

Yes, the cohort works for people shipping their first serious AI system whether the goal is to land a senior role or to launch a product. The shipped system serves both equally well.

Do I need prior AI experience?

You need to be able to code in Python or TypeScript. Complete beginners can follow the classroom they get access to before the cohort sessions to come in well-prepared.

How much time will this take?

You'll spend 3 hours every Tuesday in the live session and roughly 3 hours of async work in between, for 8 weeks. The Tuesday session time is fixed.

What does it cost?

It's a four-figure investment that we discuss during the 30-minute consult, alongside whether the cohort is the right fit for your project.

Can I do this while working full-time?

Yes, most attendees do. The live session is one Tuesday a week and the async work fits around your existing schedule, as long as you can carve out roughly 6 hours a week.

I accept those who have the highest chance of success.

In the 30-minute call we discuss your goals and whether you are ready for the program.