LangChain
The framework for building LLM-powered applications
LangChain · Frameworks
Launched Oct 2022
Quick Answer
LangChain is the framework for building llm-powered applications, made by LangChain. It is free and open source. Key uses: RAG applications, AI agents, Document Q&A.
Last updated:
Users
10M+ GitHub stars, used by 80%+ of LLM developers
Valuation
$200M (2023 funding)
Growth
Fastest-growing developer framework 2023
What is LangChain?
LangChain provides abstractions for chaining LLM calls, integrating tools and memory, building agents, and connecting to data sources. Available in Python and JavaScript.
How did LangChain get started?
Created by Harrison Chase, released Oct 2022 as a side project. Exploded in popularity as ChatGPT API launched. Became the dominant LLM framework. $25M Series A Feb 2023. $25M Series B Jun 2023. LangSmith observability platform 2023. LangGraph for stateful agents 2024. LangChain v0.3 simplification after criticism of complexity.
What's new in LangChain in 2026?
LangGraph Platform GA (2025) - deploy & scale stateful agents; LangSmith v2 with evals & prompt registry; LangChain v0.3 with simplified interface; MCP integration
How much does LangChain cost?
Open Source
Free
- Full LangChain framework
- All integrations
- LangGraph for agents
- Community support
LangSmith Starter
$0/mo
- 5,000 traces/month
- Dashboard & debugging
- Eval tools (limited)
LangSmith Plus
$39/mo
- 50,000 traces/month
- Team sharing
- Datasets & evals
- Prompt hub
LangSmith Enterprise
Custom
- Unlimited traces
- SSO/SAML
- On-prem option
- SLAs
- Dedicated support
What can you do with LangChain?
- RAG applications
- AI agents
- Document Q&A
- Chatbots
Pros
- Large ecosystem
- Many integrations
- Active community
Cons
- Steep learning curve
- Over-abstracted
- Rapid API changes
What are the best alternatives to LangChain?
Compare LangChain Head-to-Head
Frequently Asked Questions about LangChain
How much does LangChain cost?
LangChain pricing: Open Source at Free; LangSmith Starter at $0/mo; LangSmith Plus at $39/mo; LangSmith Enterprise at Custom.
Is LangChain free?
Yes, LangChain is fully free and open source.
What is LangChain used for?
LangChain is used for: RAG applications, AI agents, Document Q&A, Chatbots.
What are the best alternatives to LangChain?
Top alternatives to LangChain include LlamaIndex, Haystack, Semantic Kernel.
What platforms does LangChain support?
LangChain is available on: Python, JavaScript/TypeScript, LangGraph Platform (deployment), LangSmith (observability).
Details
Underlying Models
Platforms
Integrations
Ideal For
- LLM app developers
- RAG system builders
- AI agent researchers
- Chatbot developers