Agentic AI Comparison:
Langfuse vs LangSmith
vs
Introduction
Langfuse and LangSmith are leading LLM observability platforms for tracing, monitoring, evaluating, and debugging AI applications. Langfuse offers open-source flexibility and self-hosting, while LangSmith provides seamless integration with LangChain as a SaaS solution.
Overview
LangSmith
LangSmith is a closed-source SaaS platform tightly integrated with LangChain/LangGraph, offering fixed schemas, pre-built trace views, test cases, datasets, and cost/latency metrics for quick setup in LangChain ecosystems.
Langfuse
Langfuse is an open-source observability tool supporting broad frameworks, custom schemas, self-hosting, and features like traces, prompts, evaluations, and user feedback collection. It emphasizes developer control and avoids vendor lock-in.
Metrics Comparison
autonomy
Langfuse: 9
High autonomy through open-source nature, self-hosting options, custom schemas, and data control, allowing full independence from vendors.
LangSmith: 5
SaaS-only with fixed proprietary schema and strong LangChain ties limits autonomy; no self-hosting and potential vendor lock-in.
Langfuse excels for teams needing control and self-hosting; LangSmith suits those prioritizing managed services over independence.
ease of use
Langfuse: 8
Straightforward console for prompts/traces, quick setup with env vars, but requires more schema/infra decisions for advanced use.
LangSmith: 9
Out-of-box trace views, tests, dashboards, and minimal setup (just API keys); low friction for LangChain users.
LangSmith edges out for instant value in LangChain stacks; Langfuse close but needs more configuration for non-LangChain setups.
flexibility
Langfuse: 9
Supports mixed/custom frameworks, custom schemas, self-hosting, broad integrations beyond LangChain.
LangSmith: 6
Proprietary fixed schema optimized for LangChain/LangGraph; less flexible for custom stacks.
Langfuse wins for diverse ecosystems; LangSmith best for pure LangChain but restrictive otherwise.
cost
Langfuse: 9
Open-source with self-hosting (potentially free at scale); SaaS tier affordable, community notes fewer cost concerns.
LangSmith: 6
SaaS-only pricing; community flags scope/cost issues for larger teams, though low entry barrier.
Langfuse more cost-effective long-term via self-hosting; LangSmith simpler but potentially pricier at scale.
popularity
Langfuse: 7
Growing open-source popularity, active GitHub/community (r/AIQuality), positioned as top alternative; rising in 2025 discussions.
LangSmith: 8
Backed by LangChain (large ecosystem), frequent mentions in comparisons, strong for LangChain users; established SaaS adoption.
LangSmith leads in LangChain circles; Langfuse gaining traction as flexible open alternative.
Conclusions
Langfuse suits teams valuing open-source flexibility, self-hosting, and multi-framework support (higher overall scores: autonomy 9, flexibility 9, cost 9). LangSmith ideal for quick LangChain integration and ease (excels in ease 9, popularity 8). Choose based on stack: LangChain-heavy → LangSmith; custom/diverse → Langfuse.