LangChain

Framework for building LLM applications by composing prompts, models, retrievers, tools, and agents.

Works with AI agents:llms.txt
Ask your AI about this, with this page as the source:ChatGPT ↗Claude ↗Perplexity ↗

LangChain is an open-source framework, in Python and TypeScript, for building LLM applications and agents. It gives you one interface over many model providers and a ready-made loop for agents that call tools, so you are not writing provider-specific glue code.

The center of it is create_agent: you pass a model as a provider:model string, a list of tools (plain functions), and a system prompt, then add middleware for things like guardrails, retries or routing. Each provider integration ships as its own package (langchain-openai, langchain-anthropic and so on). Agents run on LangGraph, the lower-level orchestration runtime from the same team, which you can use directly when you need a graph that mixes fixed steps with model-driven ones. Deep Agents adds planning, subagents and a virtual filesystem on top.

From LangGraph you get durable execution, persistence, streaming and human-in-the-loop pauses. Agents can call tools on MCP servers through an adapter, and setting two environment variables sends traces to LangSmith, the company's hosted platform. The library runs wherever your code runs; LangSmith can also host agents as Agent Servers in US, EU or APAC regions, or you can run those servers yourself with Docker or Kubernetes.

The stack is several layered products (Deep Agents, LangChain, LangGraph, LangSmith), and part of the learning curve is picking the right layer. Self-hosting LangSmith itself is an Enterprise add-on, and self-run Agent Servers are not meant for serverless platforms that scale to zero.

Where it fits

How LangChain itself is built

11 tools, from its own code, website and Product Hunt page.

Who uses it

65 makers' products, each linked to the source that shows it, and 205 open-source projects that declare it in their code.

The maker says so 65Declared in code 206How evidence is collected →
Browser UseOpen-source library and cloud service that lets AI agents control a browser to complete…

“They handle all the integrations with all models (DeepSeek, Llama, gpt, claude)”

AI SDK & Agent FrameworkMaker says so +1 · source ↗
Kuration AICursor for B2B Research

“The whole ecosystem has been a great help till now. Even though we often have to develop our own. Langsmith is one of our go to tool for tracing and evaluating.”

AI SDK & Agent FrameworkMaker says so · source ↗
ComposioGives AI agents access to 1,000+ third-party tools, handling OAuth, permissions and exec…

“LangGraph by LangChain made it possible to design the agentic workflow as state-graphs providing greater control and reliability. Also, LangSmith for observabilty of the Agentic actions.”

AI SDK & Agent FrameworkMaker says so · source ↗
YouktiFinds who's ready to buy, then tells you what to do next

“Core framework for LLM orchestration, tool binding, prompt management, and embeddings. Powers the entire AI layer across all services.”

AI SDK & Agent FrameworkMaker says so · source ↗
DataboxAgentic analytics platform for you and your agents.

“We evaluated several orchestration frameworks before choosing LangGraph for Artifacts. Generating a document isn't one call and done, it's a multi-step flow: pull the data, structure the layout, apply styling, and hold state across follow-ups like "turn this into slides." The alternatives either abstracted too much away or couldn't handle that stateful, multi-step process cleanly. LangGraph gave us explicit control over each step, so a report doesn't drift into something the user didn't ask for halfway through generation.”

AI SDK & Agent FrameworkMaker says so · source ↗
reflexOpen-source Python framework for building full-stack web apps, frontend and backend, in…

“LangSmith has been a lifesaver for testing and debugging our prompt flows. It gave us the visibility we needed to make Reflex AI Builder feel smooth and reliable. Super helpful when working with complex LLM chains.”

AI SDK & Agent FrameworkMaker says so · source ↗
TiptapHeadless, extensible rich text editor toolkit built on ProseMirror, with paid cloud add-…

“The @tiptap-pro/ai-toolkit-langchain package provides tool definitions you can add to your AI agent built with LangChain.js.”

AI SDK & Agent FrameworkMaker says so · source ↗
WarestackEngineering delivery governance for GitHub organizations

“LangGraph's graph-based architecture with nodes and edges was the key on how we coordinate complex AI workflows. We're orchestrating multi-agent conversations where each node handles specific tasks (analysis, decision-making, action execution) and edges manage the flow between them. Memory lets us build operations that maintain context across conversations, while parallel execution nodes handle multiple AI operations simultaneously. The Pydantic formatted outputs ensure type-safe data flow between nodes, and the checkpoint system with PostgreSQL persistence lets us maintain state across these graph executions, so conversations can resume seamlessly even after server restarts.”

AI SDK & Agent FrameworkMaker says so · source ↗
JinaAI QA Engineer

“Langchain was again crucial in building our browser agent which has improved a ton in terms of reliability”

AI SDK & Agent FrameworkMaker says so · source ↗
OrangoIncrease user activation with an AI Agent in your product

“Langchain helps us define parts of our agent.”

AI SDK & Agent FrameworkMaker says so · source ↗
graph8Turn buyer signals into outbound that works

“We use Langchain to orchestrate our entire agent framework — from the AI inbox and SDR copilots to outbound flows and long-term memory. It helps manage complex tool use, contextual reasoning, and multi-turn interactions across our platform. Langchain has been critical to scaling structured LLM workflows with modular, maintainable logic. Grateful to the Langchain team and open-source contributors (part of pour team) pushing this ecosystem forward.”

AI SDK & Agent FrameworkMaker says so · source ↗
MeilisearchFast, typo-tolerant open-source search engine with hybrid full-text and vector search, s…

“Connects all the moving parts of our chat stack.”

AI SDK & Agent FrameworkMaker says so · source ↗
Receiptor AIBookkeeping tool that finds receipts in email and other sources, extracts and categorize…

“powers our AI workflows and makes them easy to adapt as we grow”

AI SDK & Agent FrameworkMaker says so · source ↗
Overflow AITurn questions about your donations into advanced insights

“Made connecting our AI to real data feel intuitive, not intimidating.”

AI SDK & Agent FrameworkMaker says so · source ↗
KushoAIKushoAI uses AI agents to generate and run tests for web interfaces and backend APIs. It…

“Nifty way to fine-tune LLMs to suit our AI Agent use-case.”

AI SDK & Agent FrameworkMaker says so · source ↗
AI Context FlowOne context & memory that works across all your AIs.

“Big thanks to LangChain for powering our AI development workflow! ⚡️ From chaining LLM calls to managing memory and integrations, LangChain makes building intelligent apps faster and more reliable. Couldn’t create without it! 🚀”

AI SDK & Agent FrameworkMaker says so · source ↗

Open source: a project that declares LangChain as a dependency in its public code — verifiable, but not necessarily a live product.

What makers say

48 makers on why they use LangChain, in their own words on Product Hunt.

LangGraph's graph-based architecture with nodes and edges was the key on how we coordinate complex AI workflows. We're orchestrating multi-agent conversations where each node handles specific tasks (analysis, decision-making, action execution) and edges manage the flow between them. Memory lets us build operations that maintain context across conversations, while parallel execution nodes handle multiple AI operations simultaneously. The Pydantic formatted outputs ensure type-safe data flow between nodes, and the checkpoint system with PostgreSQL persistence lets us maintain state across these graph executions, so conversations can resume seamlessly even after server restarts.
WarestackSep 2026 ↗
Langgraph helped build Super by providing a standardized framework that made the complex LLM/source interactions more manageable through a declarative graph structure. It enabled better parallelization which significantly improved response speed, while also providing full graph state/sequence debugging capabilities that made troubleshooting easier. The migration to Langgraph unlocked new capabilities like human-in-the-loop pauses for clarification and better fallback mechanisms when models fail. Additionally, Langgraph's functional API allowed developers to write more natural, sequential code for complex subgraphs while still maintaining the benefits of the graph framework.
SuperSep 2026 ↗
We evaluated several orchestration frameworks before choosing LangGraph for Artifacts. Generating a document isn't one call and done, it's a multi-step flow: pull the data, structure the layout, apply styling, and hold state across follow-ups like "turn this into slides." The alternatives either abstracted too much away or couldn't handle that stateful, multi-step process cleanly. LangGraph gave us explicit control over each step, so a report doesn't drift into something the user didn't ask for halfway through generation.
DataboxSep 2026 ↗
We use Langchain to orchestrate our entire agent framework — from the AI inbox and SDR copilots to outbound flows and long-term memory. It helps manage complex tool use, contextual reasoning, and multi-turn interactions across our platform. Langchain has been critical to scaling structured LLM workflows with modular, maintainable logic. Grateful to the Langchain team and open-source contributors (part of pour team) pushing this ecosystem forward.
graph8Sep 2026 ↗
LangGraph (by LangChain) powers our agent orchestration layer. We evaluated building a custom state machine, but LangGraph's approach to cyclic graphs with built-in tool calling and checkpointing saved us months. The ability to define complex agent workflows with conditions, branches, and human-in-the-loop — while staying in TypeScript — was the deciding factor. It's the backbone behind our visual workflow builder.
IgnitionRAGSep 2026 ↗

Loved and watch-outs

Themes that recur in makers' words and Hacker News comments, each linked to what it summarises, with how Product Hunt tags its reviews.

Most loved
  • One interface across many model providers, so switching models, prompts and chains is cheap. PHPH 2PH 3
  • A large ecosystem of document loaders, chunkers, retrievers and tool integrations for RAG and agents. PHPH 2PH 3
  • LangSmith tracing and evaluation show what an agent did and where it went wrong. PHPH 2PH 3
Watch-outs
  • Frequent breaking API changes force rewrites, and coding agents trained on older versions produce messy code for it. HNHN 2HN 3
  • Layers of abstraction make debugging slow, and many developers find calling model APIs or lighter libraries simpler. HNHN 2HN 3HN 4
  • Its built-in patterns for subagents and deep research lag current practice, such as handing off context through a file system. HNHN 2
On Product Hunt 4.9★ · 115 reviews
agentic workflow support 19model integration 12LangGraph framework 10LangSmith observability 7rapid prototyping 6scalable AI development 6RAG workflows 5flexible framework 4
Read the reviews on Product Hunt ↗

Reliability and open issues

Most wanted on GitHubOpen on 2026-10-04 in langchain-ai/langchain, with activity in the last year — issues and feature requests by 👍.

Who switches

Public pull requests on GitHub since Oct 2024 whose title says "X to Y" — real code changes moving a project from one tool to another, by developers in general. Open a row to see the pull requests.

LangGraph → LangChain3+ PRs
AI SDK → LangChain3 PRs
LangChain → LangGraph6+ PRs
LangChain → AI SDK4 PRs

Alternatives to LangChain

All alternatives by situation →

On Product Hunt, people weigh it against: OpenAI API, Langfuse, Groq.

Questions makers ask about LangChain

Does it work with TypeScript?

Yes. LangChain.js installs from npm as langchain plus @langchain/core and needs Node.js 22 or later, or Bun 1.0 or later. source ↗

Do I need a LangSmith account to use it?

No. Tracing to LangSmith is turned on by setting LANGSMITH_TRACING and an API key; agents run the same without them. source ↗

Where does LangSmith store my traces?

In the region you sign up in: the US (GCP Iowa or AWS Ohio), the EU (GCP Netherlands) or APAC (GCP Sydney). Only billing data is kept in the US regardless of region. source ↗

Can I self-host LangSmith?

Only as an add-on to the Enterprise plan. It installs on Kubernetes and needs ClickHouse, PostgreSQL and Redis, with blob storage recommended for production. source ↗

Can I deploy agents on my own infrastructure?

Yes. Package the agent as a Docker image and run it as a standalone Agent Server on Kubernetes, Docker or a VM, optionally still sending traces to LangSmith. The docs warn against serverless platforms, where scale-to-zero can lose tasks. source ↗

Will upgrades break my code?

Releases follow semantic versioning: stable APIs keep backward compatibility and breaking changes come only in major versions, with migration guides. APIs marked beta or alpha can still change. source ↗

Can agents use tools from MCP servers?

Yes. MCPAdapter in langchain[mcp] (version 1.4 or later) discovers an MCP server's tools and turns them into LangChain tools. The namespace is still in beta. source ↗

Is LangChain free?

Yes — there is a free tier a small product can run on; paid use starts at $39/seat/mo (LangSmith). source ↗

Is LangChain open source or self-hostable?

Open source, and you can self-host it. source ↗

Can AI coding agents work with LangChain?

It serves an llms.txt docs index.

Who uses LangChain?

65 makers' products we track, each with a source, and 205 open-source projects declare it in their code. source ↗