LangSmith

LangChain

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The observability and evaluation platform for LLM applications: trace every chain and agent run, build datasets and evals, and debug why your RAG or agent misbehaved — from the LangChain team. No lifecycle review is recorded for this listing. Its inclusion in the directory does not confirm current availability; check the vendor before relying on it.

Product preview

Overview

LangSmith exists because LLM apps fail in ways console.log cannot explain: an agent took a wrong tool call three steps ago, a retrieval missed the relevant chunk, a prompt edit quietly regressed everything. Smith traces every run step by step, scores it with datasets and evaluators, and versions prompts so changes are tested rather than vibes.

It is the companion to the LangChain ecosystem (where it installs with two lines) but works framework-agnostic via its API. Compared with Braintrust (evals-first) or Helicone (logging-first), Smith is the most complete loop: observe, annotate, evaluate, improve. The costs: another vendor dashboard to manage and per-seat pricing as teams grow. For any team shipping LLM features in production, some observability layer is mandatory — and Smith is the most common choice.

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Pros / Cons

Pros

Sees exactly where chains and agents fail
Evals wired to real production traces
Prompt versioning stops silent regressions
Two-line install in the LangChain stack

Cons

One more dashboard and vendor to manage
Per-seat pricing grows with the team
Deepest features assume LangChain conventions

Who it's for

Debugging agent tool-call failures

Regression-testing prompt changes

Monitoring production RAG quality

Collecting user feedback on LLM answers

Bottom line

The observability habit every production LLM team needs — Smith is where most start.

Key Features

Full trace visibility for chains & agents

Dataset + evaluation workflows

Prompt playground with versioning

Online feedback collection

Monitoring dashboards & alerts

Frequently asked questions

Is LangSmith currently available?

No lifecycle review is recorded for this listing. Its inclusion in the directory does not confirm current availability; check the vendor before relying on it.

What is LangSmith?

LangSmith is a AI Platforms tool developed by LangChain. It was introduced in 2023, and its developer is headquartered in San Francisco, USA. The observability and evaluation platform for LLM applications: trace every chain and agent run, build datasets and evals, and debug why your RAG or agent misbehaved — from the LangChain team.