LangSmith is LangChain's platform for tracing, evaluating, and deploying AI agents. See 2026 pricing tiers, key features, pros and cons, and alternatives.
Category
AI Infrastructure & MLOps
Pricing
Freemium, from Free (Developer plan); Plus from $39/seat/month
Verified
Not yet
Last updated
July 18, 2026
Founded
2023
Headquarters
San Francisco, California, United States
Free PlanWeb AppAPIAIFreemiumSelf-Hosted
Overview
LangSmith is LangChain's agent engineering platform for tracing, evaluating, debugging, and deploying LLM applications and AI agents, used across both development and production environments.
Founded by Harrison Chase and Ankush Gola in early 2023 and launched in beta that summer, LangSmith has grown from a LangChain-specific debugging tool into a framework-agnostic platform that also works with applications not built on LangChain.
Key Features
LangSmith's tracing engine captures every LLM call, tool invocation, and agent step as a nested, replayable trace with latency and token-cost data, feeding a dataset-driven evaluation system that supports LLM-as-a-judge, custom code, and human review.
A Prompt Hub and Playground turn prompts into version-controlled assets, while the Deployment module lets teams host agents as managed Agent Server endpoints with automatic scaling, uptime, and monitoring.
Pricing
LangSmith offers a free Developer plan with up to 5,000 traces per month for a single user, a $39/seat/month Plus plan with 10,000 traces included and unlimited additional seats, and a custom-priced Enterprise plan with SLAs and self-hosted or hybrid deployment options.
Usage beyond a plan's trace allowance is billed via LangChain Compute Units at $1.50 each and LangChain Storage Units at $1.00 each, covering agent compute and data storage respectively.
Key Features
Nested trace observability — Every LLM call, tool invocation, and agent step is captured as a replayable trace with latency and token-cost data.
Dataset-driven evaluation — Build test datasets and run offline or online evaluations using LLM-as-a-judge, custom code, or human review.
Prompt Hub and Playground — Version-controlled prompts can be referenced by name in code and updated without redeploying the application.
Managed agent deployment — Deploy agents as Agent Server endpoints with automatic scaling, uptime, and monitoring built in.
Automated pattern and failure detection — Trace data is automatically clustered to surface usage patterns, common behaviors, and failure modes.
Dashboards and alerting — Track cost, latency, error rates, and quality metrics from online evals through configurable dashboards and alerts.
Framework-agnostic integration — Works with applications built on LangChain, LangGraph, or entirely custom LLM application code.
Self-hosted and hybrid deployment — Enterprise customers can run LangSmith in self-hosted or hybrid environments for data residency and compliance needs.
Pros & Cons
Pros
Combines tracing, evaluation, prompt management, and agent deployment in a single platform
Framework-agnostic, so it is useful even for teams not using the LangChain framework
Free Developer tier and moderately priced Plus tier make it accessible for individuals and small teams
Backed by LangChain's substantial funding and rapid engineering headcount growth
Used by well-known enterprise customers, indicating production-grade reliability
Cons
Free Developer plan is capped at a single seat and 5,000 traces per month
Usage-based LCU and LSU charges can make costs harder to predict for high-volume agent workloads
Enterprise pricing is custom and not published, requiring a sales conversation
Deep feature set has a learning curve compared to narrower, single-purpose observability tools
Closely tied to the LangChain ecosystem's roadmap and terminology, which may feel unfamiliar to non-LangChain teams
Pricing
Developer $0/seat/month Free, pay-as-you-go after free tier
Plus $39/seat/month Monthly, self-serve
Enterprise Custom pricing Annual invoice
Frequently Asked Questions
Is LangSmith free to use?
Yes, LangSmith offers a free Developer plan for a single user with up to 5,000 traces per month. Paid Plus and Enterprise plans add more traces, seats, and enterprise features.
Who built LangSmith?
LangSmith is built by LangChain, founded in early 2023 by Harrison Chase and Ankush Gola, and launched in beta in summer 2023.
Does LangSmith require using the LangChain framework?
No, LangSmith is framework-agnostic and works with applications built on LangChain, LangGraph, or entirely custom code.
How much does LangSmith cost?
LangSmith's Plus plan costs $39 per seat per month with 10,000 traces included, while Enterprise uses custom annual pricing; usage beyond plan limits is billed via LangChain Compute Units ($1.50 each) and Storage Units ($1.00 each).
Can LangSmith deploy AI agents, not just monitor them?
Yes, LangSmith's Deployment module lets teams host agents as managed Agent Server endpoints with automatic scaling, uptime, and monitoring.
What are the main alternatives to LangSmith?
Common alternatives include Langfuse, Helicone, Arize Phoenix, Weights and Biases Weave, and Braintrust.