LangSmith

📖 What is LangSmith?

LangSmith is a developer platform for building, testing, debugging, and monitoring LLM applications. It provides full execution chain tracing, prompt evaluation frameworks, latent error analysis, and dataset testing for complex agentic workflows.

💡 Why It Matters

Debugging non-deterministic LLM chains and autonomous agents without tracing is notoriously difficult. LangSmith provides visibility into every prompt execution, token cost, latency bottleneck, and agent step across production AI applications.

🎯 Workplace Use Cases

• Tracing multi-step LLM agent executions to pinpoint exact tool call failures
• Evaluating prompt engineering iterations against curated golden benchmark datasets
• Monitoring token consumption costs and API latency metrics across production deployments
• Debugging retrieval augmented generation (RAG) context recall failures

🚀 How to Use It

Set environment variables (`LANGCHAIN_TRACING_V2=true` and `LANGCHAIN_API_KEY`), run your LLM code in Python/TypeScript, and view complete trace graphs on smith.langchain.com.

✨ Key Features

• Full execution chain visual trace logging (spans, inputs, outputs, token costs)
• Automated evaluation suites and LLM-as-a-judge scoring frameworks
• Prompt Playground for testing prompt variations against production traces
• Dataset curation tools for creating regression test suites

💳 Pricing & Plans

Free Tier: Free Developer plan includes 5,000 trace spans per month for 1 user seat.

Plan	Price	Notes
Plus	$39/user/month	Includes 50,000 trace spans/month, team collaboration, dataset sharing.
Enterprise	Custom pricing	VPC or self-hosted deployment, unlimited trace retention, SOC2 compliance.