Comparison LLM Observability & Monitoring

Langfuse vs LangSmith

Head-to-head comparison of the two leading LLM observability platforms — open-source Langfuse vs LangChain's LangSmith.

Published · Updated

TL;DR — Our Verdict

Choose Langfuse if you want open-source, self-hosted observability with no vendor lock-in. Choose LangSmith if you're already deep in the LangChain ecosystem and want the tightest integration with LangChain's tooling.

Feature Comparison

Langfuse LangSmith
Pricing freemium freemium
Starting Price $0 $0
Free Tier Yes Yes
Open Source Yes No
Self-Hosted Yes Yes
Cloud Hosted Yes Yes
Maturity growing established
Key Integrations
OpenAI LangChain LlamaIndex Vercel AI SDK
LangChain LangGraph OpenAI Anthropic

Two philosophies of LLM observability

Langfuse and LangSmith are the two most popular observability platforms for LLM applications, but they come from very different places. Langfuse is open-source-first, framework-agnostic, and designed to work with any LLM stack. LangSmith is built by the LangChain team and offers the deepest integration with the LangChain/LangGraph ecosystem. If you're not using LangChain, the decision is easy — Langfuse. If you are, it's worth understanding the tradeoffs.

Self-hosting and data control

Langfuse can be self-hosted on your own infrastructure (Postgres + ClickHouse), giving you full data sovereignty. LangSmith is cloud-only with an enterprise self-hosted option at significant cost. For teams in regulated industries or with strict data residency requirements, this is often the deciding factor.

Pricing comparison

Langfuse's free tier is generous — 50K observations/month with unlimited seats. LangSmith's free tier gives you 5K traces/month. At scale, Langfuse's self-hosted option means your only cost is infrastructure, while LangSmith's usage-based pricing can surprise you.

Tools Compared

Langfuse

growing

Open-source LLM engineering platform

Open Source freemium Free Tier
LLM tracing and debugging Prompt management Cost tracking

LangSmith

established

Developer platform for LLM application lifecycle

freemium Free Tier
LangChain ecosystem users LLM application testing and evaluation Prompt debugging and iteration

Langfuse

Full review →

Open-source LLM engineering platform

Langfuse was the strongest open-source option in the observability space, and in January 2026 it was acquired by ClickHouse. The core remains open source. If you want self-hosted tracing without vendor lock-in, start here. The cloud offering is generous on the free tier. Main gap is advanced alerting — you'll outgrow it if you need complex monitors.

Pros

  • + Open source, self-hostable
  • + Generous free tier
  • + Strong LangChain/LlamaIndex integration
  • + Active development and community
  • + Built-in prompt management

Cons

  • - Alerting is basic
  • - Smaller community than LangSmith
  • - Self-hosting requires PostgreSQL + ClickHouse

LangSmith

Full review →

Developer platform for LLM application lifecycle

LangSmith is the most full-featured observability platform if you're in the LangChain ecosystem. Tracing, evaluation, dataset management, and prompt playground are all strong. Self-hosting is available on the Enterprise plan. The downside: it's closed-source and deeply coupled to LangChain. If you're not using LangChain, the value proposition weakens significantly.

Pros

  • + Most mature tracing UI
  • + Deep LangChain/LangGraph integration
  • + Built-in evaluation framework
  • + Strong dataset management

Cons

  • - Closed source, self-hosting requires Enterprise license
  • - Tightly coupled to LangChain ecosystem
  • - Can get expensive at scale
  • - Vendor lock-in risk

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