LangSmith vs Langfuse 2026: Deep Platform vs Open Source and Self-Hosting
Quick verdict: LangSmith is our overall pick for langsmith vs langfuse.
LangSmith ($39/seat plus $1.00/LSU, 10K base traces) buys the wider platform - tracing, evaluation, deployment, engine - while Langfuse ($29/mo, 100K units) buys open-source licensing, unlimited users and a self-hosted path at every tier.
| Tool | Rating | Pricing | Best for |
|---|---|---|---|
| LangSmith Best overall Best for teams | 4.4/5 | Free $39/seat/mo (Plus) | LangSmith is the observability and evaluation platform from the LangChain team: $0/seat wi… |
| Langfuse Best free | 4.3/5 | Free $29/mo (Core) | Langfuse is the open-source-first LLM observability platform: free Hobby with 50K units a … |
Bottom line: LangSmith for teams that need observability, evaluation and deployment under one login and can live with seat-plus-unit metering and 14-to-180-day retention tiers. Langfuse for teams that need EU or on-prem residency, a real free tier, and unlimited users on every paid step. The two are closer on tracing quality than the marketing suggests; they diverge on what surrounds it. Pick Braintrust if evaluation volume is the cost driver, Arize AX for a $50 entry with unlimited evals, or Helicone for request-level visibility only.
Pricing and details
LangSmith · 4.4/5
Free plan available · $39/seat/mo (Plus)
Trace volume is metered in LangChain Standard Units (LSU) at $1.00/LSU on top of the seat fee; base traces carry 14-day retention, extended traces 180 days, and retention auto-upgrades can raise your bill
No annual pricing published on the LangSmith pricing page
LangSmith is the observability and evaluation platform from the LangChain team: $0/seat with 5K base traces a month, Plus at $39/seat with 10K, then pay-as-you-go at $1.00 per LangChain Standard Unit.
Score breakdown
Pros
- Widest platform in the cluster - tracing, monitoring, evaluation, prompt hub, deployment, sandboxes and an autonomous debugging engine under one login
- The only vendor that publishes its metering unit (LSU at $1.00) and per-resource rates, so a bill can be estimated before you commit
- 14-day base and 180-day extended retention are documented explicitly, including which actions upgrade a trace and which do not
- Native integrations for the major agent frameworks plus OpenTelemetry SDKs for Python, TypeScript, Go and Java
Cons
- Retention auto-upgrades are the bill trap: online evaluators and automation rules push matching traces to the pricier extended tier unless you opt out per evaluator
- Extended retention for SaaS tops out at 180 days as of 2026-09-14, so long-horizon analysis has to go to Enterprise customization
- Plus is $39/seat with unlimited seats, which punishes a wide read-only audience paying for observability they do not act on
Pricing verified 2026-10-03
Langfuse · 4.3/5
Free plan available · $29/mo (Core)
Usage is billed in units (100K units included on paid tiers, then $8 per additional 100K, lower at volume); a separate self-hosted pricing page exists for on-prem deployments
No published annual rate; Pro carries an optional Teams add-on at $300/mo for SSO, SSO enforcement and fine-grained RBAC
Langfuse is the open-source-first LLM observability platform: free Hobby with 50K units a month, Core at $29/mo for 100K units and 90-day retention, Pro at $199/mo with three-year retention, Enterprise at $2,499/mo.
Score breakdown
Pros
- A real free tier with no credit card: 50K units a month, all platform features, 30 days of data access and 2 users
- Core at $29/mo is by far the cheapest paid step in the cluster, with unlimited users on every paid tier
- Cloud and self-hosted deployment from the same product, so privacy-sensitive teams have a real path instead of a sales call
- Published discounts for startups, research and students, plus a documented open-source project track
Cons
- Core retains data for 90 days only - three-year retention needs the $199 Pro plan
- No deployment runtime or autonomous debugging engine, so it covers tracing and evaluation but not the agent platform around them
- The optional Teams add-on for SSO and fine-grained RBAC is another $300/mo on top of Pro
Pricing verified 2026-10-03
Frequently asked questions
Which is better overall, LangSmith or Langfuse?
LangSmith is our overall pick (4.4/5 vs 4.3/5). LangSmith ($39/seat plus $1.00/LSU, 10K base traces) buys the wider platform - tracing, evaluation, deployment, engine - while Langfuse ($29/mo, 100K units) buys open-source licensing, unlimited users and a self-hosted path at every tier.
Do LangSmith and Langfuse offer free plans?
LangSmith and Langfuse have a free tier. LangSmith paid plans start at $39/seat/mo (Plus); Langfuse paid plans start at $29/mo (Core).
What does LangSmith cost?
$39/seat/mo (Plus) — Trace volume is metered in LangChain Standard Units (LSU) at $1.00/LSU on top of the seat fee; base traces carry 14-day retention, extended traces 180 days, and retention auto-upgrades can raise your bill. Prices were last verified on 2026-10-03.