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LangSmith — AI for Software Development

Trace, monitor, and evaluate your AI agents and LLM applications with sub-second performance.

What is LangSmith?

LangSmith: Trace, monitor, and evaluate your AI agents and LLM applications with sub-second performance. It has a free plan. Zekai scores it 9.1 out of 10 after independent testing. Best for aI agent tracing and debugging.

DifferentiatorPurpose-built SmithDB delivering sub-second performance across millions of traces
Proof71ms
Try LangSmith
Free Plan
Free plan verified · free AI tools for Developers
9.1 Zekai
Agent Observability Layer
AI for Software Development
Ease of Use
8.0
Accuracy
10.0
Value
8.0
Time Saving
10.0
TracingMonitoringEvaluationSmithDBOpenTelemetry
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Zekai Verdict

What is it?
LangSmith is an agent and LLM observability platform that provides visibility into agent behavior, cost, and latency.
Best for
AI for Software Development
Not ideal for
Paid plans scale directly with trace volume which can increase costs unexpectedly
Price
Free plan
Zekai Score
9.1/10
Hand-scored by Zekai

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⚡ Quick answer

LangSmith is an agent and LLM observability platform built to trace, monitor, and evaluate AI applications. It helps development teams track cost, latency, and agent trajectories using specialized databases and flexible framework integrations.

CategoryAgent & LLM Observability Platform
Best forAI agent tracing and debugging
Free planyes
DifferentiatorPurpose-built SmithDB delivering sub-second performance across millions of traces
Proof71ms
Rating4.5
📖 About LangSmith
How It Works

Your workflow, automated

1
Integrate SDK
Add the Python, TypeScript, Go, or Java SDK to your application or connect via OpenTelemetry.
2
Capture Traces
Automatically record multi-turn chat interactions, model calls, and nested tool trajectories.
3
Analyze and Debug
Use SmithDB to query traces instantly, monitor production metrics, and evaluate agent performance.
Ready to automate your workflow with LangSmith?
Try LangSmith →
Real Impact

Before & After

❌ Before

Blindly guessing why multi-step AI agents fail in production without visibility into token counts or internal tool calls.

✅ After

Pinpointing latency bottlenecks and debugging failures instantly with step-by-step trace execution logs.

Sub-second trace queries
AI Prompts

Prompts for Developers

Prompt 01 The SQL Query Generator with Schema Context
CREATE TABLE users ( id SERIAL PRIMARY KEY, name VARCHAR(100), email VARCHAR(100) UNIQUE, created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW() ); CREATE TABLE orders ( id SERIAL PRIMARY KEY, user_id INTEGER REFERENCES users(id), amount…
Prompt 02 The MCP-Aware Database Migration Agent
(for interacting with the Prisma schema and CLI) *
Prompt 03 The Agentic E2E Test Runner
(for creating GitHub issues) Scenario: The "new user registration" feature has been deployed to the staging environment at
See all 15 AI prompts for Developers →
Social Proof

Trusted by professionals

Ease of Use
8.0
Accuracy
10.0
Value
8.0
Time Saving
10.0
Connects With

LangSmith integrations

OpenAI SDK Anthropic SDK Vercel AI SDK LlamaIndex OpenTelemetry PagerDuty
Setup complexity: Intermediate
LangSmith is an agent and LLM observability platform that provides visibility into agent behavior, cost, and latency. It allows software development teams to trace execution steps, monitor production metrics, and evaluate agent performance using SDKs for Python, TypeScript, Go, and Java.
The decision

Is LangSmith worth it?

Built for
Software Engineers, AI Engineers, DevOps Teams
Effort to adopt
Intermediate
Who It's For

Why Software Development choose this tool

🎯
Built for
AI for Software Development
In-Depth Overview
Building reliable AI applications requires deep visibility into complex execution paths, multi-turn chat interactions, and deeply nested tool calls that standard databases simply cannot query efficiently. LangSmith addresses this engineering challenge by offering purpose-built infrastructure for agent observability, helping you pinpoint the exact root causes of latency spikes, cost overruns, and unexpected model outputs. Whether you are building with native SDKs, LlamaIndex, or custom frameworks, the platform hooks into your existing architecture using lightweight asynchronous tracing that leaves your core application performance untouched. You can track critical production metrics such as token usage and error rates, set up webhooks and PagerDuty alerts, and run online evaluations to continuously score agent quality. For teams operating under strict data governance policies, LangSmith provides options for self-hosting SmithDB inside your virtual private cloud or utilizing enterprise deployment models where sensitive traces never leave your infrastructure. While the platform offers robust debugging and clustering tools to surface hidden usage patterns, it does require integrating SDKs into your codebase and managing trace volumes carefully on paid tiers. If you are serious about moving AI agents from experimental prototypes to predictable, scalable production systems, adopting a dedicated tracing and evaluation layer is an operational necessity.

Key Use Cases

👨‍💻
Debug complex agent loops
AI Engineer
Trace multi-turn chat interactions step by step to identify where agent logic fails.
15x faster search
📊
Monitor production costs
Engineering Manager
Track token usage, error rates, and latency metrics across live deployments in real time.
Real-time alerts
✓ Pros
Framework agnostic support across Python, TypeScript, Go, and Java SDKs
Asynchronous callback handler ensures zero impact on application latency
Sub-second performance across millions of deeply nested traces
Data privacy protection with no model training on user payloads
Flexible hosting options including VPC self-hosting and managed cloud
· Cons
Paid plans scale directly with trace volume which can increase costs unexpectedly
Requires code modification to integrate SDKs into custom environments
Advanced self-hosting setups require managing infrastructure components
Trace analysis learning curve for teams new to LLM observability
⚡ Editorial Verdict

LangSmith provides essential visibility into complex LLM applications with high-performance tracing and robust framework flexibility. However, managing high trace volumes and integrating SDKs into existing codebases requires careful engineering oversight.

Questions & Answers

Frequently asked questions

What frameworks and libraries does LangSmith work with?

+
LangSmith works with any LLM framework. You can trace applications built with the OpenAI SDK, Anthropic SDK, Vercel AI SDK, LlamaIndex, or custom implementations, alongside OpenTelemetry support.

Will LangSmith add latency to my application?

+
No. The LangSmith SDK uses an asynchronous callback handler that sends traces to a distributed collector so your application performance is never impacted.

Can I self-host LangSmith?

+
Yes. LangSmith offers managed cloud, bring-your-own-cloud, and self-hosted options for teams with strict data residency and security requirements.

Will you train on the data I send LangSmith?

+
No, LangSmith will not train on your data, and you retain all rights to your data.

Last reviewed:

Plans & Pricing

LangSmith pricing and plans

Free
$0
Free tier available for development and small-scale production.
Get Started Free

Prices and features are updated regularly but can change at any time — always confirm on the official website. Some links on this page are affiliate links.

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AI Directory

About LangSmith

Full Description

LangSmith is an agent and LLM observability platform that provides visibility into agent behavior, cost, and latency. It allows software development teams to trace execution steps, monitor production metrics, and evaluate agent performance using SDKs for Python, TypeScript, Go, and Java.

Editorial Verdict

LangSmith provides essential visibility into complex LLM applications with high-performance tracing and robust framework flexibility. However, managing high trace volumes and integrating SDKs into existing codebases requires careful engineering oversight.

Last reviewed:
Disclaimer
Zekai is an independent AI tools directory. We are not affiliated with, endorsed by, or officially connected to LangSmith unless clearly stated. All product names, logos, and brands are the property of their respective owners and are used for identification purposes only. The information on this page — including pricing, features, and availability — is general information, may have changed since our last review, and is not professional advice. Zekai Scores and verdicts are our editorial opinion. Some outbound links are affiliate links that may earn us a commission at no extra cost to you. Spotted outdated or incorrect information? Request a correction →
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