LangSmith
LangSmith is LangChain's hosted platform for tracing, monitoring and evaluating applications built on language models.
What LangSmith does
LangSmith records each execution of an application as a trace, which a team can open to debug a failure or collect into datasets for evaluation. On top of traces it has dashboards and alerts, annotation queues and user feedback, and automations: rules, webhooks and online evaluations. The docs list integrations with OpenAI, Anthropic, CrewAI, the Vercel AI SDK and Pydantic AI as well as LangChain's own libraries.
It is sold by seat with a monthly allowance of traces. Traces come in two kinds: base traces are kept for 14 days and extended traces for 180 days. The same plans also cover other LangSmith products, including agent deployment, which are metered separately in LangChain Standard Units.
The hosted service runs in four regions. Self-hosting on Kubernetes is an add-on to the Enterprise plan and needs a license key; it runs ClickHouse, PostgreSQL and Redis.
LangSmith: owner, license and hosting
| Fact | Value | Source and date checked |
|---|---|---|
| Owner | LangChain, Inc. | SOURCE ↗ |
| License | Proprietary. No open-source license is published for the platform; the self-hosted version requires a license key. | SOURCE ↗ |
| Self-hosting | Only as an add-on to the Enterprise plan, on Kubernetes, with a license key. It runs ClickHouse, PostgreSQL and Redis; blob storage is optional but recommended for production. | SOURCE ↗ |
| Hosted regions | GCP US (Iowa), GCP EU (Netherlands), GCP APAC (Sydney) and AWS US (Ohio), per the docs. The pricing page says only "US or EU". | SOURCE ↗ |
Each value was read from the vendor's own page on the date shown. How listings are checked
LangSmith plans and prices
LangSmith pricing, checked on . Lowest paid plan: Plus, $39 per seat a month. Free tier: Developer: 1 seat, up to 5k base traces a month, kept for 14 days. Pricing model: A monthly fee per seat plus pay-as-you-go for traces beyond the included base traces, at 0.005 LSU per base trace, where 1 LSU is $1.
| Plan | Price | Included usage | Beyond that | Data retention | Users |
|---|---|---|---|---|---|
| Developer | $0 per seat a month | Up to 5k base traces a month | 0.005 LSU ($0.005) per base trace | 14 days for base traces, 180 days for extended traces | 1 seat |
| Plus | $39 per seat a month | Up to 10k base traces a month | 0.005 LSU ($0.005) per base trace | 14 days for base traces, 180 days for extended traces | Unlimited seats |
| Enterprise | Custom pricing | Custom | Pay-as-you-go | 14 days for base traces, 180 days for extended traces | Custom seats and workspaces |
A trace is a single execution of an application: an agent, an evaluator or a playground session. Base traces have a retention period of 14 days and extended traces 180 days, on every plan; a base trace can be upgraded to an extended one for a fee. Traces beyond the included amount are pay-as-you-go at 0.005 LSU per base trace, and upgrading a base trace to an extended one costs 0.0025 LSU; the page gives both rates in a tooltip. Other LangSmith products on the same plans (Deployment, Fleet, Sandboxes) are metered in LangChain Standard Units, with 1 LSU = $1. Plus includes 1 free small serverless deployment. The page offers credits of up to $10,000 for VC-backed startups. Self-hosted and hybrid deployment are on Enterprise only.
As stated on the vendor's pricing page on . A dash means the page does not say.
LangSmith pricing history
The pricing page has been checked daily since . No price change has been recorded since then.
Where LangSmith fits
Teams building on LangChain or LangGraph that want tracing, evaluation and agent deployment from the same vendor and on one bill, and solo developers who can work within the Developer plan's 1 seat and 5,000 base traces a month.
Limits of LangSmith
It is not open source, and self-hosting is an add-on to the Enterprise plan with a license key, so a team that must keep traces on its own infrastructure has to buy the top plan. Plus is charged per seat ($39 each a month) as well as per trace. Base traces are kept for only 14 days; keeping them 180 days means paying for extended traces. Traces beyond the allowance cost 0.005 LSU ($0.005) each, a rate the pricing page shows only in a tooltip, so this site's pricing watch cannot see it change.
Alternatives to LangSmith
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Langfuse
Langfuse is an open-source platform for tracing, evaluating and managing prompts in applications built on language models.