Last updated 08-21-2026
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LangChain
LangChain ships open source frameworks and LangSmith, the commercial platform teams use to trace, evaluate, and deploy LLM agents in production. The open source stack is the most widely downloaded in the agent space, and LangSmith handles the observability and deployment layer so teams do not rebuild infrastructure for every project.
The product line spans four open source frameworks (LangChain, LangGraph, Deep Agents, and dcode) and a LangSmith suite covering observability, evaluation, deployment, Fleet no-code agents, Sandboxes for agent-generated code, LLM Gateway for model call control, and Engine for autonomous failure diagnosis. LangSmith is framework agnostic, with native tracing for popular agent frameworks, OpenTelemetry, and SDKs for Python, TypeScript, Go, and Java.
It is built for software engineers, ML teams, and platform groups shipping agent features inside real products. Customer stories cite Klarna reducing case resolution time by 80%, Monday Service achieving 8.7x faster eval feedback loops, and C.H. Robinson automating 5,500 orders per day. LangChain reports 350 million monthly open source downloads, 7,000+ active LangSmith customers, and five Fortune 10 companies on the platform.
Open source LangChain, LangGraph, Deep Agents, and dcode frameworks with 1,000+ model and tool integrations
LangSmith traces every agent step with SDKs for Python, TypeScript, Go, and Java
Turn production traces into datasets and score agents with human review or LLM-as-judge evals
Deploy LangGraph agents with durable memory, human-in-the-loop flows, and MCP or A2A support
Fleet lets non-technical teams describe recurring tasks in plain language and run them as agents
LangSmith Engine clusters production failures and proposes fixes from your traces and code
Open source LangChain framework is MIT-licensed with 350 million monthly downloads reported on the site
LangSmith covers the full agent lifecycle from tracing and evals to production deployment
Framework-agnostic observability works beyond LangChain-only stacks
Enterprise deployment options include SaaS, hybrid, and self-hosted hosting
LangSmith Deployment and Sandboxes require a Plus or Enterprise plan, not the free Developer tier.
Usage-based trace, deployment, and Engine metering can add cost quickly at scale.
Fleet and several advanced LangSmith services are not available on the free Developer plan.
Is LangChain free to use?
Yes. The LangChain open source framework is MIT-licensed and free to use. LangSmith also offers a free Developer plan at $0 per seat with 5,000 base traces per month included, then pay-as-you-go usage.
How much does LangSmith cost?
LangSmith's Developer plan is $0 per seat per month with pay-as-you-go usage after 5,000 base traces. The Plus plan is $39 per seat per month with 10,000 base traces included. Enterprise pricing is custom and requires contacting sales.
What is the difference between LangChain and LangSmith?
LangChain is the open source framework for building agents with pre-built architectures and integrations. LangSmith is LangChain's commercial agent engineering platform for observability, evaluation, deployment, and no-code agents. LangChain integrates with LangSmith through environment configuration.
Does LangSmith work with frameworks other than LangChain?
Yes. LangSmith is framework agnostic. It offers native tracing for popular agent frameworks and OpenTelemetry, so teams can observe and evaluate agents built with other stacks, not only LangChain.
What hosting options does LangSmith offer?
LangSmith offers SaaS cloud hosting with US or EU data residency on Developer and Plus plans. Enterprise customers can choose cloud, hybrid, or fully self-hosted deployments with custom SSO, RBAC, and support SLAs.
Does LangChain train on my LangSmith data?
No. LangChain states that LangSmith does not use customer traces, prompts, or outputs to train models. Organization data stays private under LangSmith's terms of service.