LangSmith
AI Agent & LLM Observability Platform
Last verified April 24, 2026About LangSmith
LangSmith is an LLM observability platform that provides tracing, monitoring, and evaluation for AI agents and LLM applications. It offers native tracing for agent frameworks, cost and latency tracking, online LLM-as-judge evals, custom dashboards, and alerts via webhooks or PagerDuty. Framework-agnostic with SDKs for Python, TypeScript, Go, Java, and OpenTelemetry support, it works with OpenAI, Anthropic, LlamaIndex, and custom stacks. Typical buyers are engineering teams building production LLM apps needing visibility into agent behavior, debugging failures, and performance optimization. Enterprise plans include self-hosted and BYOC options for data residency.LangSmith homepage Pricing
Framework coverage
Capabilities
Features LangSmith markets publicly. Inclusion means the capability is documented — not that it's best-in-class.
LLM Evaluation
Systematic testing of LLM outputs for correctness, relevance, safety, and consistency using automated scorers, rubrics, or human review.
Model Monitoring
Production monitoring for performance, drift, data quality, and fairness regressions.
Agent Tracing
End-to-end visibility into multi-step LLM agent runs: tool calls, intermediate reasoning, token usage, latency, and errors at each step.
Prompt Management
Versioning, templating, A/B testing, and deployment workflows for LLM prompts treated as production artifacts.
Drift Detection
Automated detection of distribution shift, feature drift, prediction drift, and performance degradation in deployed ML/AI models.
Industries served
Integrations
Documented by LangSmith in public product materials.
- OpenAI API
- Anthropic API
- OpenTelemetry
- LlamaIndex
Pricing
Contact for pricing
Developer free (1 seat, 5k base traces/mo); Plus $39/seat/mo (unlimited seats, 10k base traces/mo); traces $2.50/1k base (14d), $5/1k extended (400d); Enterprise custom with self-hosting.Pricing page
Pros and cons
Pros
- Framework-agnostic tracing with multiple SDKs and OpenTelemetry support.
- Built-in LLM evals, cost/latency monitoring, and production alerts.
- Enterprise self-hosted/BYOC options for data control.
Cons
- Pricing per-seat plus usage can scale quickly for large teams/high volume.
- Primary positioning tied to LangChain ecosystem despite agnostic claims.
- No explicit regulatory framework coverage documented on site.
Frequently asked
Is there a free tier?+
Yes, Developer plan free with 1 seat and 5k base traces/month.
Does it support self-hosting?+
Yes, Enterprise plan offers self-hosted and BYOC deployment.
What integrations are available?+
SDKs for Python/TS/Go/Java, OpenAI/Anthropic/Vercel AI/LlamaIndex, OpenTelemetry.
How are traces priced?+
Base traces $2.50/1k (14-day retention); extended $5/1k (400 days).
Sources
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