What is LangSmith used for?

LangSmith is an observability, tracing and evaluation platform from LangChain for debugging and improving LLM applications and AI agents in production. It is a good fit for debugging failures in LLM agents, tracking cost and latency of AI applications, and evaluating agent quality before release.

Yes. LangSmith has a free plan, and paid plans start at $39 per seat per month.

Is LangSmith open source?

No. LangSmith is proprietary (closed-source) software. Open-source alternatives to LangSmith include Opik, Arize Phoenix and Langfuse.

Can I self-host LangSmith?

Yes. Although LangSmith is closed source, it can be self-hosted on your own servers, and the vendor also offers a hosted version.

What are some alternatives to LangSmith?

LangSmith competes with Arize AI, Braintrust and Weights & Biases. For open-source options, see Enlisted's ranked list of open-source LangSmith alternatives.

LangSmith: features, pricing and alternatives

About LangSmith

LangSmith is a platform from LangChain for seeing what LLM applications and agents actually do. It records step-by-step traces so developers can find failures, track cost and latency, and measure response quality.

Tracing works natively with popular agent frameworks and OpenTelemetry, with SDKs for Python, TypeScript, Go and Java, and it supports message threading for multi-turn chats. Beyond observability, the platform offers evaluation to score agent performance, deployment for shipping agents, sandboxes for running generated code safely, an LLM gateway to control model calls, and no-code agents through Fleet. LangChain also maintains the open-source LangChain, LangGraph and deepagents frameworks.

LangSmith is a proprietary commercial service with a try-it option, a demo request and a published pricing page. It suits teams building agents with LangChain tools as well as teams using other frameworks.

Key features

Step-by-step agent and LLM tracing
Evaluation and scoring of agent performance
SDKs for Python, TypeScript, Go and Java
OpenTelemetry support
Agent deployment and sandboxes
LLM gateway for model calls

Good fit for

→Debugging failures in LLM agents
→Tracking cost and latency of AI applications
→Evaluating agent quality before release

Tags: llm-observability; tracing; evaluation; langchain; agents; llmops; monitoring; ai-infrastructure

LangSmith: questions and answers

What is LangSmith used for?: LangSmith is an observability, tracing and evaluation platform from LangChain for debugging and improving LLM applications and AI agents in production. It is a good fit for debugging failures in LLM agents, tracking cost and latency of AI applications, and evaluating agent quality before release.
Is LangSmith free?: Yes. LangSmith has a free plan, and paid plans start at $39 per seat per month.
Is LangSmith open source?: No. LangSmith is proprietary (closed-source) software. Open-source alternatives to LangSmith include Opik, Arize Phoenix and Langfuse.
Can I self-host LangSmith?: Yes. Although LangSmith is closed source, it can be self-hosted on your own servers, and the vendor also offers a hosted version.
What are some alternatives to LangSmith?: LangSmith competes with Arize AI, Braintrust and Weights & Biases. For open-source options, see Enlisted's ranked list of open-source LangSmith alternatives.