Software Development & Delivery · Preview

langchainjs

The agent engineering platform

Best fitUsers who want source-backed project understanding before installing it.

Check whether this project matches your task before installing it.

What it can doskill, recipe, host_instruction, eval, preflight

Review the portable capability path.

Before continuingVerify in a sandbox

Do not treat a preview pack as a proven local install.

GitHub snapshot18k stars

3.2k forks · 1.1k contributors

Official first step Read manual preview Source repository

Preview status · 2026-05-16

What is langchainjs?

LangChain.js is organized into a modular monorepo structure with multiple packages that serve different purposes. Each package focuses on specific functionality while maintaining interoper...
Best fit: Users who want source-backed project understanding before installing it.
Capability added to an AI workflow: skill, recipe, host_instruction, eval, preflight
Evidence base: https://github.com/langchain-ai/langchainjs, https://github.com/langchain-ai/langchainjs, https://github.com/langchain-ai/langchainjs#readme
Preview pages are noindex until English quality, canonical, and citation gates pass.
langchainjs still needs sandbox verification before production use.

Quick decision

Use this section to decide whether the project is worth a deeper read.

Best forUsers who want source-backed project understanding before installing it.

Match the project to your task before installing it.

Capabilityskill, recipe, host_instruction, eval, preflight

The agent engineering platform

Repositorylangchain-ai/langchainjs

18k stars · 3.2k forks

What it can do

Translate the upstream project into concrete capabilities the user can judge before installing.

Introduction to LangChain.js

Related topics: Getting Started, Package Architecture

Sources: [libs/langchain-core/package.json:1-35](https://github.com/langchain-ai/langchainjs/blob/main/libs/langchain-core/package.json)

Getting Started

Related topics: Introduction to LangChain.js

Sources: [README.md:1-15]()

Package Architecture

Related topics: Introduction to LangChain.js, Core Abstractions

Source: https://github.com/langchain-ai/langchainjs / Human Manual

Core Abstractions

Related topics: Package Architecture, Chat Models and LLM Providers

Sources: [libs/langchain-core/src/runnables/base.ts]()

Chat Models and LLM Providers

Related topics: Embeddings Integration, Agent Framework

Sources: [libs/providers/langchain-anthropic/src/chat_models.ts:1-100]()

Sources: https://github.com/langchain-ai/langchainjs, Human Manual, Project Pack evidence, and downstream validation signals.

Community Discussion Evidence

Project-level external discussion stays visible on the detail page, not only inside the manual.

Stars18k stars

Forks3.2k forks

Contributors1.1k contributors

Licenseunknown

Community Discussion Evidence

7 source-linked items

Review these external discussions before using langchainjs with real data or production workflows. They are review inputs, not standalone proof that the project is production-ready.

01
[Feature request] React Native support
github / github_issue
02
bug(@langchain/openai): Bare JSON.parse in Responses API converter crash
github / github_issue
03
Must pass in at least 1 record to upsert.
github / github_issue
04
@langchain/[email protected]
github / github_release
05
@langchain/[email protected]
github / github_release
06
@langchain/[email protected]
github / github_release
07
README/documentation is current enough for a first validation pass.
GitHub / issue

How to start

Only source-backed commands are shown here. Verify them in an isolated environment first.

Try the prompt first

Test the workflow without installing the upstream project.

preview

Read the Human Manual

Understand inputs, outputs, limits, and failure modes.

manual

Take context to your AI host

Use the compiled assets in your preferred AI environment.

context

Run sandbox verification

Confirm install commands and rollback before using a primary environment.

verify

npm install -S langchain

Official start command · https://github.com/langchain-ai/langchainjs#readme · verified: yes

Human Manual

The English page must expose the real manual, not a short placeholder.

8+ sections · Human Manual

langchainjs Manual

LangChain.js is organized into a modular monorepo structure with multiple packages that serve different purposes. Each package focuses on specific functionality while maintaining interoper...

Open the full manual

langchainjs Human Manual
Table of Contents
Introduction to LangChain.js
Related Pages
Architecture Overview
Core Packages
@langchain/core
libs/langchain

Introduction to LangChain.js

Related topics: Getting Started, Package Architecture

Sources: [libs/langchain-core/package.json:1-35](https://github.com/langchain-ai/langchainjs/blob/main/libs/langchain-core/package.json)

Getting Started

Related topics: Introduction to LangChain.js

Sources: [README.md:1-15]()

Package Architecture

Related topics: Introduction to LangChain.js, Core Abstractions

Source: https://github.com/langchain-ai/langchainjs / Human Manual

Core Abstractions

Related topics: Package Architecture, Chat Models and LLM Providers

Sources: [libs/langchain-core/src/runnables/base.ts]()

Chat Models and LLM Providers

Related topics: Embeddings Integration, Agent Framework

Sources: [libs/providers/langchain-anthropic/src/chat_models.ts:1-100]()

AI Context Pack and portable assets

After deciding to continue, take the project context into your own AI host.

Complete pack plus user-owned assets

These files are planning and verification assets for Claude Code, Codex, Gemini, Cursor, ChatGPT, and other AI hosts.

Download complete pack Read Human Manual

BundleComplete Project Pack AssetAI Context Pack AssetBoundary & Risk Card AssetHuman Manual AssetPitfall Log AssetPrompt Preview AssetQuick Start ManifestPROJECT_PACK.json

Preflight checks

Treat this preview as a planning asset, not proof that your local environment is ready.

The manual is generated from source-linked project files and Doramagic validation signals.
Community evidence warnings stay visible instead of being converted into marketing claims.
The preview remains noindex until English quality and reciprocal indexing gates are explicitly opened.
Use the upstream repository as the final authority for installation commands, license, and version-specific behavior.

Pitfall Log and verification risks

Doramagic surfaces high-risk items before users treat a candidate capability as verified.

high

Review upstream issue

The source signal needs review before production use.

medium

Review upstream issue

The source signal needs review before production use.

medium

Review upstream issue

The source signal needs review before production use.

medium

Review upstream issue

README/documentation is current enough for a first validation pass.

medium

Review upstream issue

The source signal needs review before production use.

medium

Review upstream issue

no_demo

medium

Review upstream issue

no_demo

medium

Review upstream issue

The source signal needs review before production use.