Langchain js env file in the root directory and add your OpenAI API key: VITE_OPENAI_API_KEY=your_openai_api_key Ensure you replace your_openai_api_key with your actual OpenAI API key. This is a plain chat agent, which simply passes the conversation to an LLM and generates a text response. In chains, a sequence of actions is hardcoded (in code). Tools are utilities designed to be called by a model: their inputs are designed to be generated by models, and their outputs are designed to be passed back to models. js that interacts with external tools. Revamped integration docs and API reference. Read more here. Create a new directory: In your terminal, run: mkdir langchain-js-app cd langchain-js-app Most of them use Vercel's AI SDK to stream tokens to the client and display the incoming messages. Join 1M+ builders standardizing their LLM app development in LangChain's Python and JavaScript frameworks. Upon successful installation, you can verify it by opening your terminal and running: node -v; This command returns the installed Node. js提供了强大的提示模板系统，使得开发者能够轻松创建和管理与LLM的交互提示。 Sep 16, 2024 · mkdir langchain-js-app cd langchain-js-app; Initialize npm: Execute the command: npm init -y; This creates a package. Get started with LangChain. To help you ship LangChain apps to production faster, check out LangSmith. LangGraph. LangChain is a framework for developing applications powered by language models. While it served as an excellent starting point, its limitations became apparent when dealing with more sophisticated and customized agents. The agents use LangGraph. The core idea of agents is to use a language model to choose a sequence of actions to take. The @langchain/mcp-adapters package provides a simple way to load MCP tools and use them with LangChain agents. Partner packages (e. In this guide, we will learn the fundamental concepts of LLMs and explore how LangChain can simplify interacting with large language models. 灵活的提示管理. LangChain provides a standard interface for agents, along with LangGraph. For a current description of this project, please see the up-to-date README at the project's new location Stream all output from a runnable, as reported to the callback system. 0 and made it the recommended way to create agents with LangChain. load method to read each file and return a Document[] array. js for building custom agents. js version. 3. Create a retrieval chain that retrieves documents and then passes them on. 12, last published: a day ago. MCP adapters provides a simple loadMcpTools function that wraps the MCP tools and makes them compatible with Sep 29, 2023 · LangChain is a JavaScript library that makes it easy to interact with LLMs. @langchain/community: Third party integrations. Sep 16, 2024 · In this article, we will explore how to effectively use JavaScript with LangChain, covering installation, basic constructs, integrations with various LLMs, and real-world application examples. The five main message types are: LangChain previously introduced the AgentExecutor as a runtime for agents. They use preconfigured helper functions to minimize boilerplate, but you can replace them with custom graphs as Jul 25, 2023 · By integrating LangChain with Node. There are 694 other projects in the npm registry using langchain. js 16, you will need to follow the instructions in this section. js. Feb 26, 2025 · LangChain is a powerful framework for building applications with large language models (LLMs). js is helpful in this scenario by abstracting out the interactions. It will pass the output of one through to the input of the next. @langchain/openai, @langchain/anthropic, etc. For specifics on how to use each package, look for their pages in the appropriate component docs section (e. Create a . Creates client objects: Azure OpenAI for embeddings and chat; Azure AI Search for the vector store This library provides a lightweight wrapper to allow Model Context Protocol (MCP) services to be used with LangChain. 11. See full list on github. js supports integration with AWS SageMaker-hosted endpoints Azure OpenAI [Azure: Bedrock: Amazon Bedrock is a fully managed: ChromeAI: This feature is experimental and is Stream all output from a runnable, as reported to the callback system. Oct 31, 2023 · LangChain provides a way to use language models in JavaScript to produce a text output based on a text input. Standard parameters Many chat models have standardized parameters that can be used to configure the model: Sep 14, 2024 · Released LangGraph. Stream all output from a runnable, as reported to the callback system. js Learn LangChain. 欢迎来到 LangChain JS 中文入门指南示例仓库！这个仓库旨在帮助开发者快速上手 LangChain JS并熟悉其使用方法。 本仓库是由 liaokongVFX编写的 LangChain 中文入门教程的 JavaScript 版本。 LangChain 介绍 LangChain是一个强大的框架，旨在帮助 Apr 28, 2025 · Load PDFs into LangChain. LangChain supports two message formats to interact with chat models: LangChain Message Format: LangChain's own message format, which is used by default and is used internally by LangChain. js 16, but if you still want to run LangChain on Node. LangChain Expression Language (LCEL): A syntax for orchestrating LangChain components. Mar 17, 2025 · LangChain. It enables applications that: 📄️ Installation. This guide covers how to do routing in the LangChain Expression Language. If you're looking to use LangChain in a Next. The serverless API endpoint: Receives the question from the user. com Apr 28, 2025 · In this tutorial, you create a LangChain. There are 411 other projects in the npm registry using langchain. Routing helps provide structure and consistency around interactions with LLMs. Remarks. js LangGraph. It’s not as complex as a chat model, and it’s used best with simple input–output Jan 5, 2024 · Within this guide, you have explored the various facets and capabilities of LangChain when utilized in JavaScript. Nov 29, 2023 · 在 LangChain 的官方文档中可以找到 LangChain 的 JS 版本所支持集成的完整 LLM 列表。 例如，你可以将 Cohere 与 LangChain 一起使用。 再使用 npm install cohere-ai 安装 Cohere 之后，你就可以像下面示例代码一样，使用 LangChain 和 Cohere 编写一个简单的问答脚本： The . Routing allows you to create non-deterministic chains where the output of a previous step defines the next step. Step 3: Install LangChain Messages LangChain provides a unified message format that can be used across all chat models, allowing users to work with different chat models without worrying about the specific details of the message format used by each model provider. Latest version: 0. You will have to make fetch available globally, either: Typescript bindings for langchain. Documentation for LangChain. json file, which will manage the dependencies for your project. Together, these products simplify the entire application lifecycle: Develop: Write your applications in LangChain/LangChain. This guide will walk through some high level concepts and code snippets for building generative UI's using LangChain. OpenAI's Message Format: OpenAI's message format. Start using langchain in your project by running `npm i langchain`. js, Deno, Supabase Edge Functions, and more. Chatbots: Build a chatbot that incorporates memory. This project has moved. js project, you can check out the official Next. Unsupported: Node. LangChain messages are classes that subclass from a BaseMessage. LangChain. To see the full code for generative UI, click here to visit our official LangChain Next. This agent works by taking in initChatModel requires langchain>=0. Most useful for simpler applications. langchain: Chains, agents, and retrieval strategies that make up an application's cognitive architecture. Anthropic; Cerebras; Cloudflare; Cohere 🚚 REPOSITORY MOVED 🚚 - new location: https://github. 📄️ Quickstart. Typescript bindings for langchain. See this guide for some considerations to take when upgrading. yarn add @langchain/community @langchain/core playwright. js documentation is currently hosted on a separate site. js document format. 4 days ago · Install LangChain. This function utilizes the LangChain. In this quickstart we'll show you how to: Stream all output from a runnable, as reported to the callback system. Hit the ground running using Templates for reference. chat models). This includes all inner runs of LLMs, Retrievers, Tools, etc. Streaming: LangChain streaming APIs for surfacing results as they are generated. 1, we recommend that you first upgrade to 0. js: Follow the installation instructions provided on the website. js MCP adapters to integrate MCP tools with LangChain. Sep 16, 2024 · Install Node. Base class for all types of messages in a conversation. Refer to the how-to guides for more detail on using all LangChain components. 2. pipe() method allows for chaining together any number of runnables. This does not have access to any tools, or generative UI components. 0 or 0. LangChain Expression Language Cheatsheet This is a quick reference for all the most important LCEL primitives. js simplifies the complexity between services. 2. We do not guarantee that these instructions will continue to work in the future. Includes an LLM, tools, and prompt. You'll Arcjet Redact: The Arcjet redact integration allows you to redact: AWS SageMakerEndpoint: LangChain. js how-to guides here. Its powerful abstractions allow developers to quickly and efficiently build AI-powered applications. js，开发者可以充分发挥诸如GPT-3等先进语言模型的潜力，同时又能根据特定需求进行定制和扩展。 LangChain. Langchain JS is a JavaScript library that simplifies the development, productionization, and deployment of applications powered by large language models (LLMs). js, LangChain's framework for building agentic workflows. Retrieve relevant documents from Azure AI Search. g. Dec 3, 2023 · 尽管在演示 LangChain 不同功能的示例中，我一直都是使用 OpenAI 模型。但其实 LangChain 并不局限于 OpenAI 模型。你可以将 LangChain 与许多其他 LLM 和 AI 服务一起使用。在 LangChain 的官方文档中可以找到 LangChain 的 JS 版本所支持集成的完整 LLM 列表。 Documentation for LangChain. Here, the prompt is passed a topic and when invoked it returns a formatted string with the {topic} input variable replaced with the string we passed to the invoke call. LangChain integrates with many providers. 📖 Documentation Please see here for full documentation, which includes: LangSmith: A developer platform that lets you debug, test, evaluate, and monitor chains built on any LLM framework and seamlessly integrates with LangChain. Oct 31, 2023 · Learn how to use LangChainJS to create and experiment with agents, models, and tools for natural language processing. In an effort to make it as easy as possible to create custom chains, we've implemented a "Runnable" protocol that most components implement. Learn LangChain. Next. js 0. Orchestration Get started using LangGraph to assemble LangChain components into full-featured applications. js is an extension of LangChain aimed at building robust and stateful multi-actor applications with LLMs by modeling steps as edges and nodes in a graph. Agents: Build an agent with LangGraph. 🦜️🔗 LangChain. You can peruse LangGraph. js agent that integrates with Azure AI Search and Azure OpenAI to answer HR-related questions. Params required to create the agent. Learn how to use Langchain JS with tutorials, how-to guides, conceptual introductions, and API reference. js: Use the loadPdfsFromDirectory function to load the documents. . js 16 We do not support Node. js template. Leveraging LangChain in JavaScript facilitates the seamless development of AI-powered web applications and provides an avenue for experimentation with Large Language Models (LLMs). com/langchain-ai/langgraphjs/tree/main/libs/langgraph-supervisor - langchain-ai/langgraph-supervisor-js Stream all output from a runnable, as reported to the callback system. The agent's architecture is designed to: Determine if a question is relevant to HR documentation. This repository contains a series of agents intended to be used with the Agent Chat UI (repo). js on Scrimba; An full end-to-end course that walks through how to build a chatbot that can answer questions about a provided document. Step 2: Initialize a New Project. js is a library for building AI applications with various tools and integrations. For more advanced usage see the LCEL how-to guides and the full API reference . This is a standard interface with a few different methods, which make it easy to define custom chains as well as making it possible to invoke them in a standard way. This is recommended by OpenAI for older models, but may not be suitable for all use cases. 📄️ Introduction. Looking for the Python version? Check out LangChain. Feb 11, 2024 · Interface. Configure OpenAI API Key. The API flow is useful to understand how LangChain. This is driven by an LLMChain. Whether to strip new lines from the input text. Deploy and scale with LangGraph Platform, with APIs for state management, a visual studio for debugging, and multiple deployment options. See the initChatModel() API reference for a full list of supported integrations. It includes properties like content, name, and additional_kwargs. 通过LangChain. 27, last published: 9 days ago. LangChain’s flexible abstractions and AI-first toolkit make it the #1 choice for developers when building with GenAI. It shows off streaming and customization, and contains several use-cases around chat, structured output, agents, and retrieval that demonstrate how to use different modules in LangChain together. ): Some integrations have been further split into their own lightweight packages that only depend on @langchain/core. js starter template. LangGraph extends LangChain by enabling graph-based workflows, making it ideal for building… 🦜️🔗 LangChain. Partner Packages These providers have standalone @langchain/{provider} packages for improved versioning, dependency management and testing. Apr 1, 2025 · Now that we have our MCP clients set up, we can use the LangChain. js, developers can harness the power of AI to process and understand vast amounts of text data, unlocking a world of possibilities in the realm of NLP. js的主要特性 1. Learn how to run it in browsers, Cloudflare Workers, Vercel/Next. js and OpenAI packages: npm install @langchain/core @langchain/openai 3. This array is a standard LangChain. js community's PDFLoader. The prompt in the LLMChain must include a variable called "agent_scratchpad" where the agent can put its intermediary work. ⚡ Building applications with LLMs through composability ⚡. Help us build the JS tools that power AI apps at companies like Replit, Uber, LinkedIn, GitLab, and more. It also includes methods like toDict() and _getType(). Explore examples of OpenAI, SerpAPI, and Calculator integrations, and how to customize and manipulate text data. Supported Environments. A great introduction to LangChain and a great first project for learning how to use LangChain Expression Language primitives to perform retrieval! Build controllable agents with LangGraph, our low-level agent orchestration framework. LangSmith Runnable interface: The base abstraction that many LangChain components and the LangChain Expression Language are built on. js supports AlephAlpha's Luminous family of models. Agents. Output is streamed as Log objects, which include a list of jsonpatch ops that describe how the state of the run has changed in each step, and the final state of the run. How to update your code If you're using langchain / @langchain/community / @langchain/core 0. Chatbot Architecture Overview Apr 11, 2023 · LangChain. lbrd fxuru inlixh dcynhh irofum umyr ljrcupf jiuuuc nwalex hwa