---
slug: "langsmith"
name: "LangSmith"
effect: "Traces, evaluates and monitors LLM apps and agents on LangChain's hosted platform via Python and JS SDKs"
category: "eval-observability"
url: "https://www.langchain.com/langsmith/observability"
github: "langchain-ai/langsmith-sdk"
pricing: "freemium"
license: "MIT (client SDKs); the LangSmith platform is a commercial hosted service"
tags: ["tracing", "evals", "monitoring", "langchain", "python", "typescript"]
platforms: []
install_kind: "pip"
date_added: "2026-10-14"
drop_score: 40
stars: 1079
pushed_at: "2026-10-14T17:56:48Z"
signals_status: "ok"
signals_fetched_at: "2026-10-15T01:19:00.286Z"
page: "https://agenttooldrop.com/tools/langsmith"
---

# LangSmith

Traces, evaluates and monitors LLM apps and agents on LangChain's hosted platform via Python and JS SDKs

Category: Evals and observability. Pricing: Free tier + paid. License: MIT (client SDKs); the LangSmith platform is a commercial hosted service.

## Why you would want it

LangSmith is LangChain's platform for debugging, evaluating and monitoring language model apps and agents; the MIT-licensed Python and JavaScript SDKs send traces to it, for example by wrapping the OpenAI client. It works with any LLM application and has a native integration with LangChain Python and LangChain JS. There is a free Developer plan with a monthly trace allowance and paid per-seat plans, with pay-as-you-go usage beyond the included traces.

## Best for

- Teams already building with LangChain
- Hosted tracing without running infrastructure
- Python and JS/TS apps

## Use it when

You want managed tracing and evals with no servers to run, especially if your app already uses LangChain.

## Skip it if

You want to self-host without an enterprise contract; self-hosted and hybrid deployment are Enterprise plan options. Usage beyond the included traces is billed pay-as-you-go.

## Editor note

The GitHub repo holds the client SDKs; the LangSmith platform itself is a hosted product.

## Install

Install the Python SDK:

```sh
pip install -U langsmith
export LANGSMITH_TRACING=true
export LANGSMITH_API_KEY=ls_...
```

Source: https://github.com/langchain-ai/langsmith-sdk#readme

## Live signals

Fetched 2026-10-15T01:19:00.286Z (status: ok).

- Repository: langchain-ai/langsmith-sdk
- Stars: 1,079
- Forks: 313
- Open issues and PRs: 248
- License (GitHub): MIT
- Last push: 2026-10-14
- Latest release: v0.14.8 (2026-10-13)

## Links

- Website: https://www.langchain.com/langsmith/observability
- GitHub: https://github.com/langchain-ai/langsmith-sdk
- Install instructions verified at: https://github.com/langchain-ai/langsmith-sdk#readme
- Source for this entry: https://github.com/langchain-ai/langsmith-sdk#readme
- AgentToolDrop page: https://agenttooldrop.com/tools/langsmith
- Full catalog (JSON): https://agenttooldrop.com/tools.json