Langfuse vs. LangSmith
This guide outlines the key differences between Langfuse and LangSmith to help engineering teams choose the right LLM observability platform.
TL;DR:
- Choose Langfuse if you prioritize Open Source (MIT), data sovereignty (full self-hosting), a framework-agnostic approach (works with any stack), and transparent unit-based pricing.
- Choose LangSmith if you are an “All-in-LangChain” shop requiring a managed SaaS solution that offers deep, native integration for deploying LangChain and LangGraph agents.
Open Source & Distribution
Langfuse is open source (MIT) and self-hosting is a first-class citizen. LangSmith is a proprietary, closed-source SaaS tool; while it offers a self-hosted option, it requires an Enterprise license.
| Feature | Langfuse | LangSmith |
|---|---|---|
| Model | Open Source (MIT License) | Proprietary SaaS (Closed Source) |
| GitHub Stars |  | N/A |
| Self-Hosting | First-Class Citizen: Full feature parity with Cloud. | Enterprise Only: Requires a sales contract and license key. |
| Data Sovereignty | High: Can run fully air-gapped on own VPC without vendor contact. | Medium: “Hybrid” deployment available for Enterprise; SaaS defaults to Cloud. |
Scalability & Performance
Both platforms utilize ClickHouse for high-scale analytics. Langfuse is part of ClickHouse and works closely with the core database team to ensure highest performance and reliability.
| Feature | Langfuse | LangSmith |
|---|---|---|
| Backend | ClickHouse (acquired Langfuse) | ClickHouse |
| Ingestion | Async Queue: Decoupled Redis queue + generic workers for reliability. | Queue-Based: Stateless backend designed for horizontal scaling. |
Integrations
LangSmith’s primary strength is its vertical integration with the LangChain framework. Langfuse positions itself as an open and framework-agnostic platform built on OpenTelemetry standards.
| Feature | Langfuse | LangSmith |
|---|---|---|
| Standard | OpenTelemetry Native: SDKs built on OpenTelemetry. | Supported: Supports OTel ingestion; features optimized for native SDK. |
| Frameworks | Integrations with 80+ frameworks and model providers (OpenAI, Vercel AI SDK, LangChain, etc.) | Ecosystem Focused: Deepest support for LangChain/LangGraph; others via wrappers and OTel. |
Pricing
The economic models differ significantly. Langfuse charges based on the depth of data (Units), while LangSmith charges based on the volume of root executions (Traces).
| Feature | Langfuse | LangSmith |
|---|---|---|
| Model | Unit-Based: 1 Unit = 1 Trace, Observation, or Score. | Trace-Based: Charges per root run (internal steps included). |
| Free Tier | 50,000 units/mo | 5,000 traces/mo. |
| Plans | Free, Core ($29/mo), Pro ($199/mo), Enterprise. | Developer (Free), Plus ($39/seat/mo), Enterprise. |
Open Platform & Extensibility
Langfuse is API-first, allowing teams to treat observability data as their own. LangSmith focuses on extending the LangChain ecosystem via the Hub.
| Feature | Langfuse | LangSmith |
|---|---|---|
| API Access | API first: Full CRUD for Traces, Spans, Scores, and platform features. | Read/Write: API available to query traces and datasets. |
| Data Export | Blob Storage Export: Automated dumps to S3/GCP (JSONL/Parquet). | Bulk Export: Available on paid plans. |
Enterprise Security
Both platforms are enterprise-ready with major certifications. Langfuse offers ISO 27001 in addition to SOC 2, and allows for easier air-gapped compliance via open-source self-hosting.
| Feature | Langfuse | LangSmith |
|---|---|---|
| Certifications | SOC 2 Type II, ISO 27001, GDPR, HIPAA aligned. | SOC 2 Type II, GDPR, HIPAA. |
| Adoption | Trusted by 19 of Fortune 50 & 63 of Fortune 500. | Wide adoption among LangChain enterprise users. |
| Governance | SSO, RBAC available in Teams/Enterprise plans. | SSO, RBAC available in Enterprise plans. |
Feature Highlights
Langfuse:
- Model Agnosticism: Works equally well with OpenAI SDK, LiteLLM, LlamaIndex, or raw HTTP calls.
- Prompt Management: Agnostic playground that doesn’t lock you into a specific framework’s syntax.
- Evaluations: “LLM-as-a-judge” evaluators that run on your own infrastructure or via the managed service.
- ClickHouse Native: Unrestricted access to raw data via SQL (in self-hosted) for custom analytics.
LangSmith:
- LangGraph Deployment: A specialized runtime to deploy LangGraph agents as APIs (DevOps capabilities).
- Zero-Setup Tracing: Automatic instrumentation for LangChain applications via environment variables.
- The Hub: Access to a community repository of prompts.
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