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Serverless AI Chat with RAG using LangChain.js

An open-source TypeScript sample application for serverless, document-grounded AI chat, built with LangChain.js and Azure services.

Explore the practical guide ↓

Independent OpenViST project profile, based on linked sources.

Serverless AI Chat with RAG using LangChain.js — OpenViST project profile in RAG & Knowledge Systems.
OpenViST project illustration. See the linked sources for product details.
Understand the project

Practical overview

When it fits

Use it as a codebase and architecture reference when developing a document-grounded chatbot, especially for a support scenario with replaceable source documents.

Who it is for

  • Developers exploring retrieval-augmented generation with LangChain.js.
  • Teams prototyping support chat that answers questions using a document collection.
  • Azure developers seeking a web chat application architecture with serverless API and storage components.

Documented uses

  • Build a chat interface that answers queries using retrieved enterprise documents.
  • Ingest documents and generate responses through a LangChain.js API.
  • Store chat sessions, extracted document text and vectors, while keeping source files in blob storage.
Before you choose

Requirements & limits

The repository is public and MIT-licensed. It can be opened through GitHub Codespaces or set up locally; using Azure-hosted components is part of the documented application architecture.

  • The sample uses Azure Static Web Apps, Azure Functions, Azure Cosmos DB for NoSQL and Azure Blob Storage.
  • Its UI is a Lit web component, and LangChain.js handles document ingestion and chat responses.
  • The provided example corpus is fictional Contoso Real Estate material and can be replaced.
  • The README describes Ollama for local development without cloud costs; cloud deployment uses Azure services.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Prepare a local development environment

Set up the documented tools and obtain a local copy of the sample repository.

Before you start

  • Node.js LTS
  • Azure Developer CLI
  • Git
  • PowerShell 7+ on Windows, or Git Bash or WSL for Azure Developer CLI commands
  • Azure Functions Core Tools if the API fails to start

Steps

  1. Fork the repository on GitHub.

  2. Copy the URL for your fork.

  3. Clone the fork from a terminal using the command below.

    Documented command
    git clone

Expected outcome

A local copy of the sample and the listed development tools needed to proceed with the README's later setup instructions.

Guide limitations

  • These steps cover environment preparation and obtaining the code, not configuring or running the application.
  • The README says to install Azure Functions Core Tools manually only if the API fails to start.
Documentation 1 ↗
Evidence and transparency

Sources & review

Official repository ↗
Source record details
Source availability
Active
Sources checked
9 October 2026
Original website title
Azure-Samples/serverless-chat-langchainjs · Official homepage title · retained in its source language
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