β‘ Building applications with LLMs through composability β‘
Looking for the Python version? Check out LangChain.
To help you ship LangChain apps to production faster, check out LangSmith. LangSmith is a unified developer platform for building, testing, and monitoring LLM applications.
You can use npm, yarn, or pnpm to install LangChain.js
npm install -S langchain
or yarn add langchain
or pnpm add langchain
LangChain is written in TypeScript and can be used in:
LangChain is a framework for developing applications powered by language models. It enables applications that:
This framework consists of several parts.
The LangChain libraries themselves are made up of several different packages.
@langchain/core
: Base abstractions and LangChain Expression Language.@langchain/community
: Third party integrations.langchain
: Chains, agents, and retrieval strategies that make up an application's cognitive architecture.Integrations may also be split into their own compatible packages.
This library aims to assist in the development of those types of applications. Common examples of these applications include:
βQuestion Answering over specific documents
π¬ Chatbots
The main value props of the LangChain libraries are:
Off-the-shelf chains make it easy to get started. Components make it easy to customize existing chains and build new ones.
Components fall into the following modules:
π Model I/O:
This includes prompt management, prompt optimization, a generic interface for all LLMs, and common utilities for working with LLMs.
π Retrieval:
Data Augmented Generation involves specific types of chains that first interact with an external data source to fetch data for use in the generation step. Examples include summarization of long pieces of text and question/answering over specific data sources.
π€ Agents:
Agents allow an LLM autonomy over how a task is accomplished. Agents make decisions about which Actions to take, then take that Action, observe the result, and repeat until the task is complete. LangChain provides a standard interface for agents, along with LangGraph.js for building custom agents.
Please see here for full documentation, which includes:
As an open-source project in a rapidly developing field, we are extremely open to contributions, whether it be in the form of a new feature, improved infrastructure, or better documentation.
For detailed information on how to contribute, see here.
Please report any security issues or concerns following our security guidelines.
This is built to integrate as seamlessly as possible with the LangChain Python package. Specifically, this means all objects (prompts, LLMs, chains, etc) are designed in a way where they can be serialized and shared between languages.