What it is
LangSmith is LangChain's commercial platform for watching and improving LLM applications. It records traces of every model call, tool call and agent step, and adds dashboards, alerts, online evaluations, annotation queues for human feedback, datasets, experiments and prompt management. It also deploys agents built with LangGraph.
It works with LangChain and LangGraph out of the box and, according to its docs, with OpenAI, Anthropic, CrewAI, the Vercel AI SDK and Pydantic AI through SDKs or integrations. It accepts OpenTelemetry traces, so other instrumented apps can send data too.
The free Developer plan is one seat with 5,000 base traces a month. Plus costs $39 per seat per month with 10,000 base traces, then pay-as-you-go. Base traces are kept 14 days; extended traces 180 days, cut from 400 days for new SaaS traces on 14 September 2026. Self-hosting and hybrid deployment are Enterprise-only.
Our review
LangSmith is the strongest choice if you build on LangGraph and the weakest value if you do not. Its traces understand LangGraph's structure natively, its evaluation and annotation tools are mature, and it can deploy the same agents it observes, which none of the open-source tracing tools we cover does.
Pricing works against growing teams and large volumes alike. Plus charges $39 for every seat, billed on the 1st with no credit for seats removed mid-month, where Langfuse and Opik charge by usage. Trace overage is pay-as-you-go, but the per-trace rates are not shown on the pricing page or in the billing docs, which say only that extended traces cost more than base ones, so price a realistic month in LangChain's calculator before committing. Base traces are kept 14 days and extended traces 180, down from 400 for new SaaS traces from 14 September 2026; anything needed for longer has to be copied into a dataset.
Deployment billing changed on 1 October 2026 to usage-based pricing in LangChain Standard Units, at $1 each. You pay for requested vCPU and memory, not what is used: an idle Dedicated Small deployment on GCP costs about 0.53 LSU an hour, which is roughly $390 a month before any traffic. Plus includes one free Small Serverless deployment. The newer Engine feature, which reviews traces and proposes fixes, costs about 7 to 45 LSU a run, so it needs a budget of its own.
Self-hosting is the other dividing line. LangChain's docs say the cloud service is SOC 2 Type II, HIPAA and GDPR compliant, offers US and EU regions, and does not train on customer traces. Teams that cannot send prompts and responses to a third party at all must buy Enterprise for the hybrid or self-hosted options, whereas Langfuse, Phoenix and Opik can be self-hosted for free. OpenTelemetry support means LangSmith is no longer tied to LangChain code, but deployments, the agent server and the deepest trace views all still assume LangGraph.
Where it earns its place
A four-engineer team shipping a LangGraph support agent
Debug multi-step agent failures and gate releases on evaluations
Plus at $39 a seat is $156 a month with 10,000 base traces included; traces show each graph node and tool call, and datasets turn bad runs into regression tests. The included free Small Serverless deployment can host the agent itself.
An ML platform lead at a fintech running agents on several frameworks
Centralise traces from CrewAI, the Vercel AI SDK and in-house code
Send OpenTelemetry traces to LangSmith's EU region. Budget for overage at volume, since the per-trace rate is not public, and copy audit-relevant runs to datasets before the 180-day limit deletes them.
A head of engineering at a healthcare company
Trace an agent that handles patient messages
The cloud service is listed as HIPAA compliant, but a BAA is not mentioned in the public docs, so confirm it with sales; if prompts cannot leave the company, only Enterprise's self-hosted or hybrid option fits.
Before you commit
- Setup
- Set an API key and an environment variable, and LangChain or LangGraph apps start sending traces; other stacks use the SDKs or OpenTelemetry.
- Integrations
- LangChain, LangGraph, OpenAI, Anthropic, CrewAI, the Vercel AI SDK and Pydantic AI through SDKs or integrations, plus any OpenTelemetry-instrumented app.
- Data and privacy
- SOC 2 Type II, HIPAA and GDPR per the docs; US or EU cloud regions; no training on customer data. Self-hosted and hybrid deployment are Enterprise-only.
- Cost at scale
- A ten-seat team on Plus pays $390 a month in seats before trace overage; an idle Dedicated Small deployment adds about $390 a month.
- Limits
- Base traces deleted after 14 days and extended after 180; the Developer plan is capped at 5,000 traces a month until a card is added.
What's good
- Deepest tracing and debugging for LangGraph agents
- Mature evaluation, datasets and annotation queues
- Accepts OpenTelemetry traces from any framework
- SOC 2 Type II, HIPAA and GDPR, with US and EU regions
- Can deploy the agents it observes
What's not
- $39 per seat on Plus, with no credit for seats removed mid-month
- Per-trace overage rates not published on the pricing page
- Self-hosting only on Enterprise
- Extended trace retention cut to 180 days
- Dedicated deployments bill for idle capacity
Best for
Teams building production agents on LangChain or LangGraph who want hosted tracing, evaluation and deployment from one vendor.
Alternatives
LangSmith: common questions
- Is LangSmith worth it?
- Deep, mature tracing and evaluation for LangGraph agents, sold per seat at a price that rewards small teams with big budgets. We rate it 4.2 out of 5.
- How much does LangSmith cost?
- Developer free (1 seat, 5,000 base traces/month). Plus $39/seat/month (10,000 base traces, then pay-as-you-go; one small serverless deployment). Enterprise custom, with hybrid or self-hosted options. Base traces kept 14 days, extended traces 180 days.
- What are the downsides of LangSmith?
- $39 per seat on Plus, with no credit for seats removed mid-month; per-trace overage rates not published on the pricing page; self-hosting only on Enterprise; extended trace retention cut to 180 days; dedicated deployments bill for idle capacity.
- Who is LangSmith best for?
- Teams building production agents on LangChain or LangGraph who want hosted tracing, evaluation and deployment from one vendor.
- How much does LangSmith cost for a team or in production?
- A ten-seat team on Plus pays $390 a month in seats before trace overage; an idle Dedicated Small deployment adds about $390 a month.
- Is LangSmith safe for company data?
- SOC 2 Type II, HIPAA and GDPR per the docs; US or EU cloud regions; no training on customer data. Self-hosted and hybrid deployment are Enterprise-only.
- What are the best LangSmith alternatives?
- The closest alternatives we have reviewed are Braintrust.
Answers checked Oct 22, 2026.
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