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LangSmith 101

A practical guide series for learning LangSmith - the platform that lets you see exactly what your LLM app did, test it against real examples instead of vibes, and fix a bad prompt without redeploying. Written by people who build agents for a living.

Foundations → Practitioner · ~36 minutes total
1 trace app call LLM run Tool run Project trace Dataset + eval

One request in your app becomes one trace in LangSmith - every LLM call, tool call, and retriever step nested inside it.

FOUNDATIONS

Start Here

Never opened LangSmith, or opened it once and got lost? These two guides get you oriented.

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What Is LangSmith? (And Why Observability Matters)

The plain-English version: what problem it solves, how it relates to LangChain and LangGraph, and why "it worked when I tested it" isn't good enough.

Foundations 5 min read
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Core Concepts: Traces, Runs & Projects

Three ideas that cover almost everything - once these click, the whole dashboard makes sense.

Foundations 6 min read
HANDS-ON

Build Something

Time to see your own app's traces show up, not just read about it.

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Setting Up Tracing In Your App

A hands-on walkthrough - API key, environment variables, the @traceable decorator, and your first trace.

Hands-On 7 min read

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ADVANCED

Make It Production-Ready

The two things that separate "I glanced at some traces" from an app you'd actually trust in production.

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Evaluations & Datasets: Testing LLM Apps On Purpose

Turning real traces into a test suite, and how LLM-as-judge evaluators score things a plain assertion can't.

Advanced 7 min read
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Prompt Playground & Prompt Hub

Iterating on prompts without redeploying code, and how versioned commits keep production from breaking mid-edit.

Advanced 6 min read
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Monitoring and Alerts in Production

Watching latency, error rate, and cost continuously once you're live, and running evaluators on real traffic.

Advanced 6 min read