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Installation

info

Updating from <0.0.52? See this section for instructions.

Supported Environments​

LangChain is written in TypeScript and can be used in:

  • Node.js (ESM and CommonJS) - 18.x, 19.x, 20.x
  • Cloudflare Workers
  • Vercel / Next.js (Browser, Serverless and Edge functions)
  • Supabase Edge Functions
  • Browser
  • Deno
  • Bun

Installation​

To get started, install LangChain with the following command:

npm install -S langchain

TypeScript​

LangChain is written in TypeScript and provides type definitions for all of its public APIs.

Loading the library​

ESM​

LangChain provides an ESM build targeting Node.js environments. You can import it using the following syntax:

import { OpenAI } from "langchain/llms/openai";

If you are using TypeScript in an ESM project we suggest updating your tsconfig.json to include the following:

tsconfig.json
{
  "compilerOptions": {
    ...
    "target": "ES2020", // or higher
    "module": "nodenext",
  }
}

CommonJS​

LangChain provides a CommonJS build targeting Node.js environments. You can import it using the following syntax:

const { OpenAI } = require("langchain/llms/openai");

Cloudflare Workers​

LangChain can be used in Cloudflare Workers. You can import it using the following syntax:

import { OpenAI } from "langchain/llms/openai";

Vercel / Next.js​

LangChain can be used in Vercel / Next.js. We support using LangChain in frontend components, in Serverless functions and in Edge functions. You can import it using the following syntax:

import { OpenAI } from "langchain/llms/openai";

Deno / Supabase Edge Functions​

LangChain can be used in Deno / Supabase Edge Functions. You can import it using the following syntax:

import { OpenAI } from "https://esm.sh/langchain/llms/openai";

We recommend looking at our Supabase Template for an example of how to use LangChain in Supabase Edge Functions.

Browser​

LangChain can be used in the browser. In our CI we test bundling LangChain with Webpack and Vite, but other bundlers should work too. You can import it using the following syntax:

import { OpenAI } from "langchain/llms/openai";

Updating from <0.0.52​

If you are updating from a version of LangChain prior to 0.0.52, you will need to update your imports to use the new path structure.

For example, if you were previously doing

import { OpenAI } from "langchain/llms";

you will now need to do

import { OpenAI } from "langchain/llms/openai";

This applies to all imports from the following 6 modules, which have been split into submodules for each integration. The combined modules are deprecated, do not work outside of Node.js, and will be removed in a future version.

  • If you were using langchain/llms, see LLMs for updated import paths.
  • If you were using langchain/chat_models, see Chat Models for updated import paths.
  • If you were using langchain/embeddings, see Embeddings for updated import paths.
  • If you were using langchain/vectorstores, see Vector Stores for updated import paths.
  • If you were using langchain/document_loaders, see Document Loaders for updated import paths.
  • If you were using langchain/retrievers, see Retrievers for updated import paths.

Other modules are not affected by this change, and you can continue to import them from the same path.

Additionally, there are some breaking changes that were needed to support new environments:

  • import { Calculator } from "langchain/tools"; now moved to
    • import { Calculator } from "langchain/tools/calculator";
  • import { loadLLM } from "langchain/llms"; now moved to
    • import { loadLLM } from "langchain/llms/load";
  • import { loadAgent } from "langchain/agents"; now moved to
    • import { loadAgent } from "langchain/agents/load";
  • import { loadPrompt } from "langchain/prompts"; now moved to
    • import { loadPrompt } from "langchain/prompts/load";
  • import { loadChain } from "langchain/chains"; now moved to
    • import { loadChain } from "langchain/chains/load";

Unsupported: Node.js 16​

We do not support Node.js 16, but if you still want to run LangChain on Node.js 16, you will need to follow the instructions in this section. We do not guarantee that these instructions will continue to work in the future.

You will have to make fetch available globally, either:

  • run your application with NODE_OPTIONS='--experimental-fetch' node ..., or
  • install node-fetch and follow the instructions here

You'll also need to polyfill ReadableStream by installing:

npm i web-streams-polyfill

And then adding it to the global namespace in your main entrypoint:

import "web-streams-polyfill/es6";

Additionally you'll have to polyfill structuredClone, eg. by installing core-js and following the instructions here.

If you are running Node.js 18+, you do not need to do anything.