LangChain
LangChain is an open source framework for building applications powered by language models, providing abstractions for chains, agents, tools and memory across many model providers. The framework itself is free; LangChain the company also runs LangSmith, a paid platform for observability, evaluation and deployment of LLM applications, with a free developer tier and paid plans from $39 a seat a month.
Facts checked on against the sources listed at the end of this page.
- Pricing
- FreemiumPaid from $39 a seat a month for LangSmith Plus, plus usage-based compute and storage
- Open source
- YesMIT
- GitHub stars
- 147,504
- npm downloads a week
- 3.8Mup 15% on the week before
- Latest release
- langchain-core…1 day ago
- Releases in 90 days
- 10about 3 a month
A good fit for
- Developers building LLM applications who want a provider-agnostic framework
- Teams building agents that need to orchestrate multiple tools and steps
- Projects that want built-in tracing and evaluation through LangSmith as they move to production
- Applications that may need to switch model providers without rewriting application logic
Not a good fit for
- Very simple single-call LLM integrations, where LangChain's abstractions can add more complexity than needed
- Teams that specifically want a retrieval-and-indexing-first framework rather than a general orchestration framework, where LlamaIndex may fit better
- Projects that want to avoid any paid platform dependency, if they plan to rely on LangSmith's paid tiers for production observability
LangChain pricing
The LangChain framework is free and open source. LangSmith, the paid observability and deployment platform, has a free Developer tier (up to 5,000 traces a month, 1 seat) and a Plus tier at $39 a seat a month with usage-based compute and storage charges on top; Enterprise pricing is custom.
| Plan | Price | What you get |
|---|---|---|
| LangChain framework | $0, open source | Chains, agents, memory and integrations under the MIT license. |
| LangSmith Developer | $0 a seat a month | Up to 5,000 base traces a month, 1 seat, community support. |
| LangSmith Plus | $39 a seat a month | Up to 10,000 base traces a month, unlimited seats, 1 free small deployment, plus usage-based compute and storage. |
| LangSmith Enterprise | Custom pricing | Self-hosted or hybrid deployment, custom SSO, ABAC/RBAC, support SLA. |
Prices in USD, checked on 27 September 2026. Current prices on langchain.com.
Main features
- Chains and agents
- Compose sequences of LLM calls and tool use, or let an agent decide which steps and tools to use.
- Provider-agnostic integrations
- Swap between many LLM providers and vector stores with a consistent interface.
- LangGraph
- A library for building stateful, multi-step agent workflows as graphs.
- Memory
- Built-in patterns for maintaining conversation history and context across turns.
- LangSmith tracing
- Paid platform for observing and debugging chains and agents in production.
- Evaluation
- LangSmith tooling for running evaluations against test datasets to measure application quality.
About LangChain
LangChain provides building blocks for LLM applications: prompt templates, chains that sequence calls together, agents that decide which tools to use, memory for multi-turn conversations, and integrations with many model providers and vector stores. It's provider-agnostic, so the same application logic can often switch between models with minimal changes.
The company behind LangChain also builds LangSmith, a separate paid platform for tracing, evaluating, debugging and deploying LLM applications, including agents built with LangChain's LangGraph library. LangSmith usage is billed through a mix of seat pricing and usage-based compute (LangChain Compute Units) and storage (LangChain Storage Units) charges.
LangChain is widely used for building chatbots, retrieval-augmented generation systems and autonomous agents, and is commonly compared with LlamaIndex, which focuses more narrowly on data ingestion and retrieval for LLM applications.
- Made by
- LangChain, Inc.
- Free plan
- Yes: the LangChain framework is free and open source; LangSmith has a free Developer tier with up to 5,000 base traces a month
- Available on
- Python, JavaScript/TypeScript, Works with most major LLM providers
Usage and activity
Weekly npm downloads of langchain, last 12 months.
Recent releases
- langchain-core==1.6.71 day ago
- langchain-text-splitters==1.1.35 days ago
- langchain-openai==1.6.71 week ago
- langchain-anthropic==1.7.51 week ago
- langchain-core==1.6.61 week ago
- langchain-fireworks==1.7.01 week ago
LangChain alternatives
LangChain compared
LangChainvsLlamaIndex
LangChain is an open source framework for building LLM applications through chains, agents, tools and memory, paired with LangSmith, a paid observability and deployment platform.
LangChainvsOpenAI
LangChain is an open source framework that provides abstractions for chains, agents, tools and memory so developers can build applications across many different LLM providers, including OpenAI.
Questions about LangChain
Is LangChain free?
Yes, the LangChain framework itself is open source under the MIT license and free to use. LangSmith, the separate observability and deployment platform, has paid tiers starting at $39 a seat a month.
What is LangSmith?
LangSmith is LangChain's paid platform for tracing, debugging, evaluating and deploying LLM applications, including agents built with LangGraph.
LangChain vs LlamaIndex, what's the difference?
LangChain is a general framework for chains, agents and tool orchestration across model providers. LlamaIndex focuses more specifically on data ingestion, indexing and retrieval for LLM applications, though both frameworks now overlap in agent features.
What languages does LangChain support?
Official libraries exist for Python and JavaScript/TypeScript.
Sources and links
Work on LangChain? Claim this listing. Something wrong or out of date? Suggest a correction. Stats come from the public GitHub and npm APIs and update every day.