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Lesson 1 of 6 10 min +50 XP

The AI Backend Stack

You're a backend developer. You know databases, APIs, and how to ship features. Now everyone wants AI in their app. The good news? You don't need to become an ML engineer. You need to learn how to integrate AI into your existing stack.

This course is for you if:

You want to add AI features to your backend without a PhD. We'll focus on practical integration, not model training.

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What's Changed for Backend Devs?

Before 2023, adding "AI" meant hiring ML engineers, training models, and managing infrastructure. Now? You make API calls.

Before (2020)
    • Hire ML team
    • Collect training data
    • Train custom models
    • Deploy on GPU clusters
    • Months of work
Now (2025)
    • Call an API
    • Send a prompt
    • Get response
    • Ship feature
    • Hours of work

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The Modern AI Backend Stack

Your Backend LLM API OpenAI / Claude Vector DB pgvector / Pinecone Your Data Postgres / Docs

These three components combine to enable RAG (Retrieval-Augmented Generation)

The Three Core Components

1. LLM API

The "brain" - processes text, generates responses, understands context

2. Vector Database

Stores text as numbers, enables "search by meaning"

3. Your Data

Documents, knowledge base, database content to ground AI responses

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When to Use AI vs Traditional Code

This is the most important decision you'll make. AI is not a replacement for code - it's a tool for specific problems.

Task Use Why
Calculate order total Traditional code Deterministic, exact math needed
Summarize customer feedback LLM Unstructured text, needs understanding
User authentication Traditional code Security-critical, must be exact
Classify support tickets LLM Fuzzy categories, natural language
Search products by name Traditional search Exact matching works fine
Search "shoes for hiking" Vector search Intent-based, semantic matching
Rule of Thumb:

If you can write clear if/else rules for it, use traditional code. If the rules are fuzzy or the input is natural language, consider AI.

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Real AI Features You Can Build

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Document Q&A

Chat with your docs, answer questions from knowledge base

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Semantic Search

Find content by meaning, not just keywords

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Content Generation

Product descriptions, email drafts, summaries

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Classification

Categorize tickets, detect sentiment, route requests

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What You'll Learn in This Course

LLM APIs Lesson 2 Prompts Lesson 3 Vectors Lesson 4 RAG Lesson 5-6

By the end, you'll build a Document Q&A bot - a complete RAG application that answers questions from your own documents.

Key Takeaways

  • AI integration is about APIs - not training models
  • Use AI for fuzzy problems - natural language, classification, generation
  • Use traditional code for exact problems - math, auth, CRUD
  • The stack is simple - LLM API + Vector DB + Your Data

Next up: Calling LLM APIs - your first AI integration.

🧠 Quick Quiz

Test your understanding of this lesson.

1

When should you use an LLM instead of traditional code?

2

What is the purpose of a vector database in AI applications?

3

What does RAG stand for?