Agent Testing

Test and evaluate your agents systematically

Build evaluation harnesses that verify agent behavior across diverse scenarios.

Test long-running agent systems with structured datasets and automated evaluation metrics to catch issues before production.

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LangSmith evaluation harness showing agent test results

How LangSmith agent harnesses work

1

Build test datasets

Create evaluation datasets with test cases covering the scenarios your agents face. Use real production traces as a foundation.

2

Run evals on your agents

Execute evaluations using custom rubrics, LLM-as-judge scorers, or coded evaluators. Compare versions to measure improvements.

3

Deploy with confidence

Integrate evaluation gates into your deployment pipeline. Only ship agents that pass your quality thresholds.

LangSmith powers top engineering teams, from AI startups to global enterprises

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Writer
Harvey
Vanta
Abridge
Clay
Rippling
Mercor
Listen Labs
dbt Labs
Klarna
Headspace
Lyft
Coinbase
Rakuten
LinkedIn
Elastic
Workday
Monday.com

Built for AI Agent Testing at Scale

Teams trust LangSmith to evaluate and improve their most critical agent systems

50M+
LLM Calls Traced
1B+
Events Ingested per Day
100K+
Monthly active orgs in LangSmith SaaS

LangSmith Agent Evaluation Platform

Test, evaluate, and improve your agent systems with structured harnesses

Comprehensive traces reveal exactly what your agent did, what tools it called, and where it failed. Understand execution flow to design better evaluation harnesses and catch edge cases.

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LangSmith Observability interface showing trace details

Built for Enterprise

Security and compliance at scale

LangSmith meets the demanding security, performance, and collaboration requirements of large organizations building AI applications at scale.

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Granular permissions

Role-based access control with org-level permissions and project isolation to meet your security and compliance requirements.

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SOC 2 Type II

Third-party security certification with comprehensive security controls.

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Self-hosted deployment

Self-hosting options to maintain full control over your AI data and meet strict compliance requirements.

Why top AI teams choose LangSmith for agent testing

Systematic evaluation

Build evaluation datasets and harnesses that test agent behavior across diverse scenarios. Measure quality objectively before and after changes.

Faster debugging

Trace every agent decision and tool call. Identify failures quickly and iterate on improvements with full visibility into execution.

Framework agnostic

Test any agent architecture. LangSmith works with your preferred framework, custom code, or multi-step agentic systems.

Customers

Elastic

"Working with LangSmith on the Elastic AI Assistant had a significant positive impact on the overall pace and quality of our development and shipping experience. We couldn't have delivered the product experience our customers now have without LangSmith—and we couldn't have done it at the same pace without it."

James Spiteri, Director of Security Product Management at Elastic

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Rakuten

"What we really needed was a more structured way to test new approaches, something better than just shipping and seeing what happened. LangSmith gave us a more scientific, structured way to understand what was actually working, whether that meant running pairwise evaluations or digging into why accuracy jumped from 70% to 80%. Our engineers especially love the intuitive debugging experience, it's saved us a lot of time."

Yusuke Kaji, General Manager of AI for Business Development at Rakuten

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Get a Demo of LangSmith for Agent Testing

See how LangSmith evaluation harnesses help you systematically test and improve your AI agents.