LangSmith
Tracing, evals and monitoring for LLM apps and agents.
Updated
✨ Try AgentScout's free AI image generator →Good for: automating workflows, evaluating agents, monitoring agents in production
Use cases
About LangSmith
LangSmith is listed in our evals & observability category and is aimed at builders. Tracing, evals and monitoring for LLM apps and agents. Pricing, as the maker states it: Free tier + paid plans. Maturity: Mature. We last checked the official link on 2026-10-14.
What is LangSmith?
LangSmith is LangChain's platform for tracing, evaluating and monitoring LLM apps and agents.
The Python client nests every LLM call in a pipeline under a single trace in the LangSmith UI.
Sources: the official README and our directory listing, checked 2026-10-18. Official site: langchain.com/langsmith.
Who is LangSmith for?
Developers who need visibility into LLM apps, with or without LangChain.
LangSmith at a glance
- Open source: Yes (MIT License)
- GitHub: langchain-ai/langsmith-python · 15 stars (as of Oct 21, 2026)
Key features
- Tracing
- Evals
- Monitoring
- Python client
LangSmith pricing
- Developer: $0/seat/mo · 1 seat, then pay as you go
- Plus: $39/seat/mo · includes 10K traces, then pay as you go
- Enterprise: Custom
Usage is billed in LangChain Standard Units ($1.00 per LSU). Startup credits of up to $10,000 are offered.
Source: official pricing page, checked Oct 18, 2026. Prices change; check the source before buying.
LangSmith FAQ
What is LangSmith?
LangSmith is LangChain's platform for tracing, evaluating and monitoring LLM apps and agents.
Who is LangSmith for?
Developers who need visibility into LLM apps, with or without LangChain.
Is LangSmith free?
Yes. LangSmith has a free option (Developer), according to its pricing page (checked Oct 18, 2026).
How much does LangSmith cost?
As of Oct 18, 2026, LangSmith's official pricing page lists: Developer: $0/seat/mo; Plus: $39/seat/mo; Enterprise: Custom. Usage is billed in LangChain Standard Units ($1.00 per LSU). Startup credits of up to $10,000 are offered.
Is LangSmith open source?
Yes. LangSmith is released under the MIT License, according to its GitHub repository.
What are alternatives to LangSmith?
Similar tools include Langfuse, MLflow, Arize Phoenix, AgentOps, Arize AI and Opik.
Compare
LangSmith ratings and reviews
Be the first to rate LangSmith: tap 1 to 5 stars below. A written review is optional.
LangSmith alternatives
Other evals & observability tools in our directory. See all evals & observability tools →
Langfuse
Open-source LLM observability, tracing and evals.
MLflow
Open-source platform for tracing, evaluating and managing agents, LLM apps and ML models.
Arize Phoenix
Open-source tracing and evaluation for LLM apps.
AgentOps
Monitoring and session replay for AI agents.
Arize AI
Agent observability and evaluation platform with tracing, evals and experiments for improving AI agents.
Opik
Comet's open-source platform for tracing, evaluating and monitoring LLM apps, RAG systems and agent workflows, self-hosted or in the cloud.
Related lists
🏆 See also: Best AI Agent Observability & Eval Tools · All best-of lists
🧭 Task guides: AI eval and benchmark tools
💲 Estimate API cost: compare per-request and monthly costs for GPT, Claude, Gemini and Grok models.
Badge for makers
Built LangSmith? Add this badge to your README or site. It links back to this page. About badges
