LangChain.js Has a Free API — Build AI Agents in JavaScript

LangChain.js is the JavaScript/TypeScript framework for building LLM-powered applications. Chains, agents, RAG, memory — everything you need for production AI apps. Quick Start npm install langchain @langchain/openai import { ChatOpenAI } from ' @langchain/openai ' ; const model = new ChatOpenAI ({ modelName : ' gpt-4o-mini ' , temperature : 0 , }); const response = await model . invoke ( ' What is TypeScript? ' ); console . log ( response . content ); Prompt Templates import { ChatPromptTemplate } from ' @langchain/core/prompts ' ; const prompt = ChatPromptTemplate . fromMessages ([ [ ' system ' , ' You are a {role}. Respond in {language}. ' ], [ ' user ' , ' {question} ' ], ]); const chain = prompt . pipe ( model ); const result = await chain . invoke ({ role : ' senior developer ' , language : ' English ' , question : ' Explain closures ' , }); Output Parsers import { StructuredOutputParser } from ' langchain/output_parsers ' ; import { z } from ' zod ' ; const parser = StructuredOu