How to beginner · 3 min read

LangSmith pricing

Quick answer

LangSmith offers a free tier with limited usage for tracing and observability of AI calls. Paid plans scale based on usage volume and features, with pricing details available on the official LangSmith website. Use the LangSmith Client to integrate and monitor your AI workflows efficiently.

PREREQUISITES

Python 3.8+
LangSmith API key
pip install langsmith

Setup

Install the langsmith Python package and set your API key as an environment variable to start using LangSmith for AI observability.

bash

pip install langsmith

Step by step

Use the LangSmith client to initialize tracing in your AI application. The free tier allows basic tracing, while paid plans unlock advanced features and higher usage limits.

python

import os
from langsmith import Client, traceable

# Set your LangSmith API key in environment variable LANGSMITH_API_KEY
client = Client(api_key=os.environ["LANGSMITH_API_KEY"])

@traceable
def run_ai_task(prompt: str) -> str:
    # Simulate AI call
    return f"Response to: {prompt}"

result = run_ai_task("Hello LangSmith pricing")
print(result)

output

Response to: Hello LangSmith pricing

Common variations

You can integrate LangSmith tracing with LangChain or other AI frameworks by setting environment variables LANGCHAIN_TRACING_V2 and LANGCHAIN_API_KEY. Async usage and custom project names are supported.

python

import os
os.environ["LANGCHAIN_TRACING_V2"] = "true"
os.environ["LANGCHAIN_API_KEY"] = os.environ["LANGSMITH_API_KEY"]
os.environ["LANGCHAIN_PROJECT"] = "my-project"

# Now all LangChain calls are automatically traced

from langchain_openai import ChatOpenAI
chat = ChatOpenAI(model="gpt-4o-mini")
response = chat.invoke([{"role": "user", "content": "Hello"}])
print(response.content)

output

Hello

Troubleshooting

If you see authentication errors, verify your LANGSMITH_API_KEY environment variable is set correctly.
For missing traces, ensure LANGCHAIN_TRACING_V2 is enabled and your project name is set.
Check LangSmith's official pricing page for updated usage limits and plan details.

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Key Takeaways

LangSmith provides a free tier with basic tracing and paid plans for higher usage and features.
Set environment variables to enable automatic tracing in LangChain and other frameworks.
Always secure your API key via environment variables to avoid authentication issues.

Verified 2026-04

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