LangChain Quickstart: Build Powerful LLM (ChatGPT/GPT4) Applications

Learn the basics of LangChain in Python

Venelin Valkov
7 min readMay 9


Ready to quickly start with LangChain? In this tutorial, you’ll learn the basics of LangChain and how to get started with building powerful apps using OpenAI and ChatGPT. We’ll start by setting up a Google Colab notebook and running a simple OpenAI model. Then, we’ll dive deeper by loading an external webpage and using LangChain to ask questions using OpenAI embeddings and ChatGPT.

Finally, we’ll explore prompt templates and chains, and combine all the components we’ve learned to create a powerful retrieval-based question-answering system. By the end of this tutorial, you’ll have a solid understanding of LangChain and how to use it to build your own language models. So let’s get started!

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What is LangChain?

LangChain is a tool that helps create programs that use language models. Language models are computer programs (such as ChatGPT) that can understand human language and respond accordingly. LangChain makes these programs more powerful by connecting them to other sources of information and allowing them to interact with their surroundings. It is written in the Python programming language and is designed to be easy to use for people who are just starting out.

If you want to build a language-based app that goes beyond simple keyword matching or rule-based systems, LangChain is the…