LangChain Fundamentals: Building Retrieval-Augmented Generation (RAG) Apps — PickAClass
★ 5.0 (5) ⏱ 3h 📚 30 lessons 🎧 Audio version

LangChain Fundamentals: Building Retrieval-Augmented Generation (RAG) Apps

Learn how to connect large language models to external data sources using LangChain components, enabling powerful and accurate custom AI applications.

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About this course

Need to build AI applications that rely on custom, up-to-date, or proprietary data? Retrieval-Augmented Generation (RAG) is the essential pattern for grounding LLMs and providing accurate, context-specific answers. This course provides a foundational, text-based understanding of the RAG architecture and how to implement it using LangChain. You will move from basic LLM interactions to constructing complex chains that retrieve relevant documents, process them, and generate high-quality, verifiable responses, setting the stage for developing advanced AI agents. What you'll learn: * Understand the core concepts of RAG, including document loading, chunking, embeddings, and vector stores. * Practice using LangChain components (Chains, Prompts, Models, Retrievers) to structure complex workflows. * Configure various data sources (loaders) and optimize document preprocessing for effective retrieval. * Apply prompt engineering techniques to guide the LLM using retrieved context effectively. * Build and test a complete, end-to-end RAG application capable of answering questions based on custom documents. The course begins with defining LLM limitations and the necessity of RAG, progressing quickly into hands-on exercises using Python and the LangChain framework. We cover setting up vector databases and designing efficient chains for robust data interaction. This course is designed for beginner developers and data scientists who want to integrate custom data into large language models. No prior experience with LangChain or vector databases is required, only basic proficiency in Python programming. Start mastering the techniques required to build context-aware AI applications today.

Course contents

6 modules · 30 lessons · 3h

1 Introduction to RAG & LangChain
Understand why RAG is necessary and set up the development environment.
5 lessons · 30 min
  1. The Limits of LLMs
    LLMs suffer from hallucinations and lack access to private or recent data.
    6 min
  2. What is RAG?
    Retrieval-Augmented Generation bridges the gap between static models and dynamic data.
    6 min
  3. Meet LangChain
    LangChain is a framework designed to simplify building LLM-powered applications.
    6 min
  4. Setting Up Your Environment
    Install Python, LangChain, and necessary libraries to start coding.
    6 min
  5. Your First LLM Call
    Write a simple script to interact with an LLM using LangChain.
    6 min
2 Data Ingestion: Loading and Splitting
Learn how to bring external data into your application and prepare it for processing.
5 lessons · 30 min
  1. Introduction to Document Loaders
    Document Loaders standardize data from various formats into a common format.
    6 min
  2. Loading PDFs and Text Files
    Use specific loaders to extract content from common document types.
    6 min
  3. The Need for Chunking
    Large documents must be split into smaller pieces to fit LLM context windows.
    6 min
  4. Recursive Character Splitting
    Use the RecursiveCharacterTextSplitter for intelligent, context-aware splitting.
    6 min
  5. Optimizing Chunk Size and Overlap
    Balance context retention and retrieval precision by tuning splitting parameters.
    6 min
3 Embeddings and Vector Stores
Transform text into searchable mathematical vectors and store them efficiently.
5 lessons · 30 min
  1. Understanding Text Embeddings
    Embeddings represent the semantic meaning of text as high-dimensional vectors.
    6 min
  2. Choosing an Embedding Model
    Compare different embedding providers and models for your specific use case.
    6 min
  3. Introduction to Vector Stores
    Vector databases allow for efficient similarity searches across millions of documents.
    6 min
  4. Setting Up ChromaDB
    Initialize a local vector store to save your processed document chunks.
    6 min
  5. Performing Similarity Search
    Query your vector store to find the most relevant chunks for a given question.
    6 min
4 LangChain Building Blocks
Master the components used to structure complex AI workflows.
5 lessons · 30 min
  1. Models: LLMs vs. ChatModels
    Understand the difference between completion models and instruction-tuned chat models.
    6 min
  2. Prompt Templates
    Create reusable and dynamic prompt structures for consistent LLM behavior.
    6 min
  3. Output Parsers
    Extract structured data (like JSON) from raw LLM text responses.
    6 min
  4. Introduction to LCEL
    LangChain Expression Language (LCEL) provides a declarative way to compose chains.
    6 min
  5. Building Your First Chain
    Combine a prompt and a model into a single executable workflow.
    6 min
5 Constructing the RAG Pipeline
Connect retrieval and generation into a unified question-answering system.
5 lessons · 30 min
  1. The Retriever Interface
    A Retriever is a generic interface that wraps vector stores for easier use in chains.
    6 min
  2. Combining Context and Query
    Design a workflow that fetches context before sending it to the LLM.
    6 min
  3. Prompt Engineering for RAG
    Instruct the LLM to use only the provided context to answer questions.
    6 min
  4. Designing Efficient RAG Chains
    Build a robust chain that takes a question and returns a context-grounded answer.
    6 min
  5. Handling Missing Information
    Teach your RAG system to say 'I don't know' when the answer isn't in the data.
    6 min
6 Refinement and Final Project
Optimize your RAG application and build a complete end-to-end solution.
5 lessons · 30 min
  1. Adding Memory to RAG
    Enable your application to remember previous questions in a conversation.
    6 min
  2. Verifiable Responses
    Modify your chain to return the sources used to generate the answer.
    6 min
  3. Testing and Evaluation
    Manually test your RAG system with edge cases and verify accuracy.
    6 min
  4. Capstone: The Ingestion Script
    Build a script that automatically processes a folder of documents into a vector store.
    6 min
  5. Capstone: The Query Interface
    Build the final interface that allows users to ask questions against the stored data.
    6 min
Final project

Personal Knowledge Assistant

You will build a command-line tool that takes a directory of your own documents (PDFs/Text), indexes them, and allows you to ask questions about their content with source citations.

What you'll get

  • 📜 Certificate of completion
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  • ⚡ Short & focused
    3h of practical content

Certificate of completion

Every course you complete on PickAClass issues a credential like this — original, with its own code, verifiable by URL, and detailed about what was actually demonstrated.

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has successfully demonstrated mastery of
LangChain Fundamentals: Building Retrieval-Augmented Generation (RAG) Apps
Skills demonstrated
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Behavioral pattern analysis
Foundational
1.2 hrs
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Performance detail
Coursework summary
Lessons completed 14 / 14
Practice questions 26 / 28
Assignments submitted 4 (avg 4.5 / 5)
Capstone project Reviewed — 4.6 / 5
Total practice 6.2 hrs
Performance benchmark
Cohort rank Top 12% of 1,625
Time to completion 11 days (median: 22)
Mastery score 91 / 100
Practice-question score 94%
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Issued under the academic standards of PickAClass. Skill levels reflect assessed performance against the course's competency rubric. This is an original credential of this platform.

Reviews (5)

Lukas Fischer DE Verified learner
★ 5 · September 1, 2026

Ich wollte schon länger verstehen, wie man ein LLM sinnvoll mit einer eigenen Wissensdatenbank verbindet, und dieser Kurs hat genau das geliefert. Die Erklärung, wie LangChain die Verbindung zwischen Sprachmodell und externen Datenquellen organisiert, war für mich der eigentliche Aha-Moment. Besonders hilfreich fand ich die praktischen Übungen, bei denen man Schritt für Schritt eine eigene RAG-Anwendung aufbaut. Die Konzepte werden zunächst einfach erklärt und dann Stück für Stück komplexer, sodass man nie das Gefühl hat, den Anschluss zu verlieren. Am Ende hatte ich ein funktionierendes kleines Projekt, das ich direkt für die Suche in eigenen Dokumenten nutzen konnte.

Rafael Pinto BR Verified learner
★ 5 · July 9, 2026

Sempre tive dificuldade em entender como conectar modelos de linguagem a fontes externas de dados, mas esse curso deixou o processo muito mais claro. A explicação sobre como o LangChain organiza os pipelines de recuperação de informação foi o ponto alto para mim. Os exercícios práticos de construção de um app RAG do zero ajudam bastante a fixar o conteúdo, sem ficar preso só na teoria. Gostei também do ritmo, dá pra acompanhar mesmo sem ter muita experiência prévia com essas ferramentas. No final consegui montar meu próprio protótipo de busca sobre documentos internos usando exatamente o que foi ensinado.

Felipe González AR
★ 5 · July 6, 2026

Explican de forma muy clara cómo usar LangChain para conectar modelos de lenguaje con fuentes de datos externas y construir una app RAG funcional.

Manon Moreau FR Verified learner
★ 5 · June 1, 2026

LangChain का उपयोग करके RAG ऐप बनाना इतना आसान लगा, हर स्टेप बहुत साफ तरीके से समझाया गया है।

Emma Wagner LU Verified learner
★ 5 · May 26, 2026

Connecter un modèle à mes propres documents avec les composants LangChain pour faire du RAG est enfin devenu clair et concret.

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