Skip to content
EDWartens UK

Free course · AI and machine learning

RAG and Chatbots with LangChain

A skill AI job posts name again and again, built properly: a chatbot that answers from PLC and drive manuals, cites the page, refuses what it cannot find, and is measured on a test set. Loading and chunking, embeddings and hybrid search, the RAG chain, query translation, routing, re-ranking, evaluation, LangGraph agents and serving — on free models throughout.

See the modules

Free to learn. Verifiable certificate £19 when you pass the final exam (optional, VAT included).

Level
Intermediate
Modules
12
Video
15 hours
Price
Free

Outcome

What you will be able to do

Build a LangChain RAG pipeline end to end: load and chunk manuals with metadata, embed locally and search with hybrid retrieval and a re-ranker, generate cited answers with a refusal rule, handle follow-up questions, route questions between documents and a database, evaluate recall, correctness and refusal on a real test set, add a bounded corrective loop with LangGraph, and serve it with Streamlit or FastAPI — hosted or fully local.

  • Load, clean and chunk vendor manuals so parameter tables survive
  • Embed locally, search with hybrid BM25 + vector retrieval and re-rank with a cross-encoder
  • Build a RAG chain that cites (doc p.N), refuses with NOT FOUND and handles follow-ups
  • Route questions between manuals and a read-only database, with structured output
  • Measure recall@k, correctness and refusal on a thirty-question test set, and improve one thing at a time
  • Add a bounded corrective loop with LangGraph and serve the assistant, hosted or fully local

Software

Google Colab or a laptop; LangChain, sentence-transformers, FAISS; a free OpenRouter key or Ollama.

Hardware

None. A laptop with 8 GB RAM for the fully local build.

Syllabus

12 modules

Each module has video lessons, notes and a short quiz. The final exam closes the course.

  1. 1What RAG is, and what it fixes4 lessons
  2. 2LangChain: models, prompts, chains1 lesson
  3. 3Loading and chunking documents1 lessonLab
  4. 4Embeddings, vector stores and hybrid search2 lessonsLab
  5. 5The basic RAG chain and chat memory1 lessonLab
  6. 6Better queries: multi-query, fusion, decomposition, HyDE5 lessons
  7. 7Routing and structured data2 lessonsLab
  8. 8Re-ranking and advanced indexing3 lessons
  9. 9Evaluating a RAG system1 lessonLab
  10. 10Agentic RAG with LangGraph3 lessonsLab
  11. 11Build, serve, keep private2 lessons
  12. 12Final assessment0 lessons

How it works

How this course works

  1. Watch the video lessonsOne module at a time, at your own pace.
  2. Take the module quizA short quiz at the end of each module shows what stuck.
  3. Keep your notesWrite in My notes beside each module and ask the trainer if you are stuck.
  4. Practise in the labOptionalTry a task from the module in the EDWartens Lab, in your browser.
  5. Sit the final examPass it once you have been through the modules.
  6. Certificate, if you want oneOptionalPaid, and only after you pass. Anyone can check it online.

EDWartens Lab

Practise this in the EDWartens Lab

Tune a document assistant by hand: set the chunking and retrieval so it cites the right section, make it refuse when the documents are silent, and keep an agent safe.

Works alongside RAG and Chatbots with LangChain. The Lab is ai for industry practice in your browser: no install, no hardware, free to use. Sign in as a learner and it opens with your account.

Open the free lab See the Lab
AI for industry: Build AI models.

Levels to try with this course

Optional. Skip it whenever you like: it never blocks your progress or your certificate.

Why practise in a lab

Technical work is judged on what you can do: wiring, commissioning, finding a fault. Doing a task yourself teaches more than watching it a second time, and a lab lets you try it safely before you meet real equipment. It does not replace working on real hardware.

  • Practise safely, so a mistake costs nothing.
  • The lab checks your work like a site test, so you know when it is right.
  • Free, in your browser, with nothing to install.

Certificate

An optional certificate when you pass

Learning is free. Pass the final exam and you can have a certificate for £19, including VAT, with a number employers can check online. It records that you completed a free online course; it is not a regulated qualification or a CPD certificate.

  • Your name, the course, its study time and your final exam score
  • A unique certificate number and a QR code to its verification page
  • Issued by Wartens Ltd; add it to your LinkedIn profile in one click
  • Pay now or after you pass: it is issued the moment you pass the final

How the certificate works

Sample certificate for RAG and Chatbots with LangChain

Credits

Who made the lessons

The video lessons belong to their creators. EDWartens wrote the study plan, notes, quizzes and the final exam.

Questions

About this course

What do I need before this course?
Comfortable Python and the ideas from the Generative AI course — tokens, prompts, embeddings. If you have done those two courses you are ready.
Do I need a paid API?
No. Hosted models come from OpenRouter's free tier; embeddings and the re-ranker run locally with sentence-transformers; FAISS is local. The fully local build with Ollama needs nothing online at all.
What are the projects?
A manual-reading assistant over three vendor manuals with citations, a re-ranker, a thirty-question evaluation and a Streamlit page; and an assistant over a year of maintenance work orders that routes text questions to RAG and counting questions to templated SQL.
Why so much on evaluation?
Because a RAG demo is easy and a RAG tool is not. The service desk in the project will accept the assistant when the numbers say recall above 0.85 and refusal at 1.0 — that is the standard the course teaches you to reach and to prove.
Is the course really free?
Yes. Every module, practice task, project and assessment. You create an account so your progress is saved and the assessments can be marked. The certificate is the only paid item, and only if you want it.
What certificate do I get?
An EDWartens Certificate of Completion, issued when you have finished the modules and passed the final assessment (the project is optional practice), with a verification code anyone can check. It is not a vendor credential and is never described as one.
Who made the video lessons?
The creators named in the Credits block at the foot of this page, on their own YouTube channels. EDWartens did not make the videos and the creators are not affiliated with EDWartens. What EDWartens wrote is the study plan, the notes, the practice tasks, the projects and the assessments.

Applied AI engineer

Take it with

See the whole path

The Professional Module is five live days of Siemens PLC, HMI and SCADA with an instructor, then a resume session and a CPD certificate.

See the Professional Module