Chat Models

npm install @langchain/openai

import { ChatOpenAI } from "@langchain/openai";

const model = new ChatOpenAI({
  model: "gpt-4o",
  temperature: 0.7,
  apiKey: process.env.OPENAI_API_KEY, // defaults to process.env.OPENAI_API_KEY
});

const response = await model.invoke("Tell me a joke about programming");
console.log(response.content);

const stream = await model.stream("Count from 1 to 10");

for await (const chunk of stream) {
  console.log(chunk.content);
}

import { z } from "zod";
import { tool } from "@langchain/core/tools";

const weatherTool = tool(
  async ({ location }) => {
    return `The weather in ${location} is sunny and 72°F`;
  },
  {
    name: "get_weather",
    description: "Get the current weather for a location",
    schema: z.object({
      location: z.string().describe("The city and state, e.g. San Francisco, CA"),
    }),
  }
);

const modelWithTools = model.bindTools([weatherTool]);
const result = await modelWithTools.invoke("What's the weather in San Francisco?");

npm install @langchain/anthropic

import { ChatAnthropic } from "@langchain/anthropic";

const model = new ChatAnthropic({
  model: "claude-3-5-sonnet-20241022",
  temperature: 0.7,
  apiKey: process.env.ANTHROPIC_API_KEY,
});

const response = await model.invoke("Explain quantum computing in simple terms");
console.log(response.content);

import { HumanMessage } from "@langchain/core/messages";

const response = await model.invoke([
  new HumanMessage({
    content: [
      { type: "text", text: "What's in this image?" },
      {
        type: "image_url",
        image_url: {
          url: "https://example.com/image.jpg",
        },
      },
    ],
  }),
]);

npm install @langchain/google-genai

import { ChatGoogleGenerativeAI } from "@langchain/google-genai";

const model = new ChatGoogleGenerativeAI({
  model: "gemini-2.0-flash-exp",
  temperature: 0.7,
  apiKey: process.env.GOOGLE_API_KEY,
});

const response = await model.invoke("Write a haiku about coding");
console.log(response.content);

npm install @langchain/mistralai

import { ChatMistralAI } from "@langchain/mistralai";

const model = new ChatMistralAI({
  model: "mistral-large-latest",
  temperature: 0.7,
  apiKey: process.env.MISTRAL_API_KEY,
});

const response = await model.invoke("Explain the concept of recursion");
console.log(response.content);

npm install @langchain/cohere

import { ChatCohere } from "@langchain/cohere";

const model = new ChatCohere({
  model: "command-r-plus",
  temperature: 0.7,
  apiKey: process.env.COHERE_API_KEY,
});

const response = await model.invoke("Summarize the benefits of TypeScript");
console.log(response.content);

npm install @langchain/groq

import { ChatGroq } from "@langchain/groq";

const model = new ChatGroq({
  model: "llama-3.3-70b-versatile",
  temperature: 0.7,
  apiKey: process.env.GROQ_API_KEY,
});

const response = await model.invoke("What are the advantages of functional programming?");
console.log(response.content);

npm install @langchain/community

import { ChatFireworks } from "@langchain/community/chat_models/fireworks";
import { ChatDeepInfra } from "@langchain/community/chat_models/deepinfra";
import { ChatMinimax } from "@langchain/community/chat_models/minimax";