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LangSmith

Freemium
llmopsobservabilityai developer toollangchaindebuggingllm evaluationprompt engineeringmachine learningai monitoring

LangSmith is a unified developer platform for debugging, testing, evaluating, and monitoring LLM applications, providing full observability into complex chains and agents to help ship reliable, production-grade AI products.


LangSmith is an observability and testing platform designed specifically for developers building applications with large language models (LLMs). It addresses the 'black box' problem by providing detailed, step-by-step traces of every run, showing exactly what prompts, tools, and model outputs were involved. Primarily serving AI engineers and MLOps teams, the platform enables them to debug failures, optimize for cost and latency, and rigorously test their applications against predefined datasets. Its unique value lies in its deep, native integration with the LangChain framework, providing a near zero-configuration observability experience for developers within that ecosystem. Beyond debugging, LangSmith facilitates a continuous improvement loop by allowing developers to collect human feedback, curate datasets from production runs, and monitor performance over time.

Pros

  • Deep, native integration with the LangChain framework for seamless, out-of-the-box observability.
  • Provides full trace visibility into LLM chains and agents, including prompts, tools, and token counts for easy debugging.
  • Comprehensive evaluation suite for testing LLM applications against custom datasets to ensure quality and prevent regressions.
  • Enables collection of human feedback and curation of datasets directly from production runs.
  • The LangSmith Hub facilitates sharing and collaboration on versioned prompts, a key MLOps practice.

Cons

  • Can be tightly coupled with the LangChain ecosystem, which might be a drawback for teams committed to other frameworks.
  • Usage-based pricing for traces and evaluations can become expensive for high-volume applications, making costs less predictable.
  • The user interface can be complex for beginners due to the density of information and features.
  • While it supports other frameworks, the ease of autoinstrumentation is significantly higher with LangChain.

Key features

  • LLM Run Tracing & Debugging
  • Automated & Custom Evaluation Suite
  • Production Monitoring & Logging
  • Human-in-the-loop Feedback Collection
  • Prompt Hub for versioning and collaboration
  • Dataset Management from production traces
  • Cost, Latency, and Token Usage Tracking

Integrations

LangChain (Python, JS/TS)OpenAIAnthropicGoogle AI (Vertex AI, Gemini)Amazon BedrockHugging FacePineconeWeaviate

Target audience

AI/ML engineers, data scientists, and software developers building, deploying, and maintaining applications that use Large Language Models (LLMs), particularly those using the LangChain framework.


Ratings & Reviews

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Key Metrics

Founded

2023

Headquarters

San Francisco, USA

Pricing Tiers

Community

Up to 5,000 trace events per month. Includes core tracing, testing, and monitoring features for individuals and small teams.

Free

Pro

Includes a higher base limit of 10,000 trace events/mo, plus pay-as-you-go pricing for additional traces, evaluations, and feedback. Adds organization-level access controls and priority support.

$20/mo + usage

Enterprise

Custom pricing for large-scale deployments. Includes features like SSO, dedicated support, custom data retention policies, and options for private deployment.

Custom


Frequently Asked Questions


Top Alternatives to LangSmith

Arize AI

Choose for a broader ML observability platform that supports traditional ML models alongside LLMs, ideal for teams wanting a single solution for all model types.

Weights & Biases

A good choice for teams already using W&B for experiment tracking, as its Prompts tool integrates LLM evaluation directly into their existing MLOps workflows.

Datadog LLM Observability

The best option for organizations already standardized on Datadog for APM, allowing them to monitor LLMs within their existing observability platform.

UpTrain

An open-source and enterprise tool focused heavily on evaluating and refining LLM applications with a wide range of pre-built checks and visualizations.

Ready to get started?

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