Evaluation · Updated 2026-10-25
LangSmith — what it is actually for
LangSmith provides tracing, datasets, evaluators, annotation queues, prompt management, and deployment for LLM applications. It offers a free Developer tier and a per-seat Plus plan.
Short answer: use LangSmith when you need debugging agent and chain traces. It is a free tier + per-seat subscription + usage service from LangChain; the official pricing source is linked below.
- Vendor
- LangChain
- Category
- Evaluation
- Pricing model
- Free tier + per-seat subscription + usage
- Free option
- Yes. Developer is free with 1 seat and 5,000 base traces per month.
What LangSmith is used for
- Debugging agent and chain traces
- Offline and online evaluations
- Prompt iteration and dataset management
Source: official product page and official documentation.
Who LangSmith is for
- Teams building and operating agents
- LangChain and LangGraph users
- Eval-driven development workflows
Source: official documentation.
Who it is not for
- Teams that need a fully self-hosted free product
- Projects that only need basic log storage
Source: documented plans, limits, and deployment model on the official product page.
Pricing
- Developer is free with 1 seat and 5,000 base traces per month.Source: www.langchain.com
- Plus is US$39 per seat per month with 10,000 base traces per month; Enterprise pricing is custom.Source: www.langchain.com
- Usage beyond the included traces is billed. One LangChain Standard Unit (LSU) is priced at US$1.Source: www.langchain.com
Base traces have shorter retention; longer retention and advanced features consume extended-retention or other metered units.
Full pricing page: https://www.langchain.com/pricing
Alternatives to LangSmith
- Braintrust — Evaluation, logging, and prompt playground for AI products.
- Arize Phoenix — Open-source LLM tracing and evaluation, with a managed cloud.
- W&B Weave — Tracing and evaluation for LLM apps inside the Weights & Biases platform.
Official sources
LangSmith FAQ
Is LangSmith free?
Yes. The Developer plan is free with 1 seat and 5,000 base traces per month.
What does LangSmith do?
It provides tracing, datasets, evaluators, annotation queues, prompt management, and deployment for LLM applications.
How much is LangSmith Plus?
Plus is US$39 per seat per month and includes 10,000 base traces per month. Usage beyond that is billed.