LangSmith vs Langfuse: a neutral 2026 comparison

Q: What is the main difference between LangSmith and Langfuse?

The core difference is licensing and hosting. LangSmith is a proprietary, closed-source SaaS from LangChain, tightly integrated with the LangChain framework, with self-hosting gated behind an Enterprise plan. Langfuse is MIT-licensed open source that anyone can self-host for free and is framework-agnostic via OpenTelemetry. Feature-wise both offer tracing, datasets, evals, and monitoring.

Q: Is Langfuse or LangSmith better for self-hosting?

Langfuse is generally easier and cheaper to self-host: it is MIT-licensed and self-hosts for free with docker compose. LangSmith self-hosting requires an Enterprise agreement. If free self-hosting and data residency are priorities, Langfuse (or another open-source tool like Langprobe) is the stronger fit.

Q: Is there an alternative to both LangSmith and Langfuse?

Yes. Langprobe is an open-source (Apache-2.0), self-hosted alternative that adds capabilities neither has: replay (edit a broken run, re-run it against a real model, and diff span by span with a determinism verdict) and an agent-native MCP surface so an agent can debug an agent.

The two most-cited LLM observability tools, compared on the axes that actually decide a purchase — licensing, self-hosting, pricing model, framework coupling, and evals.

Last updated: July 4, 2026

TL;DR

LangSmith — proprietary SaaS by LangChain; tightest fit with the LangChain framework; self-hosting is Enterprise-only. Best if you're all-in on LangChain and want a managed, first-party tool.
Langfuse — MIT open source; free self-hosting; framework-agnostic via OpenTelemetry; mature community. Best if you want open source, data residency, and prompt management.
Both are observability dashboards. Neither lets you edit and re-run a broken run against a real model — that's the gap Langprobe fills with replay + an agent-native MCP loop.

LangSmith vs Langfuse comparison table

Dimension	LangSmith	Langfuse
License	Proprietary / closed	MIT open source
Free self-hosting	Enterprise only	Yes
Managed cloud	Yes (primary)	Yes (optional)
Framework coupling	LangChain-first	Framework-agnostic
OpenTelemetry ingestion	Partial / SDK-first	Yes — OTLP/HTTP
Tracing & spans	Yes	Yes
Datasets & evals	Yes	Yes
Prompt management	Yes	Yes
Replay / re-run a broken run	No	No
Best for	LangChain-native teams	Open-source, self-hosted teams

This table reflects public positioning as of mid-2026 (see DataCamp: Langfuse vs LangSmith and Langfuse's own comparison). Pricing and self-hosting terms change — confirm on each vendor's site.

How to choose

Pick LangSmith if your stack is built on LangChain/LangGraph and you want the first-party, fully managed tool with vendor support, and you don't need to self-host for free.

Pick Langfuse if you want open source you can self-host at no cost, framework independence through OpenTelemetry, strong prompt management, and a large community.

Consider a third option if your real problem is debugging, not just observing. Both tools show you a failed run; neither lets you change it and re-run it.

When neither fits: replay-first debugging

Langprobe is an open-source (Apache-2.0), self-hosted option that keeps the tracing/eval foundation both incumbents have and adds what they lack:

Replay — edit a prompt, model, or tool config on a broken run, re-run it against a real model, and get a span-level diff plus a determinism verdict.
Agent-native MCP surface — token-budgeted, LLM-legible reads so a coding agent can find → read → replay → diff hands-free.
Open ingestion — plain OTLP/HTTP, LangSmith-compatible endpoints, no proprietary SDK.

Langprobe vs LangSmith → · Langprobe vs Langfuse →

Frequently asked questions

What is the main difference between LangSmith and Langfuse?

Licensing and hosting. LangSmith is a proprietary closed-source SaaS by LangChain, tightly integrated with the LangChain framework, with Enterprise-only self-hosting. Langfuse is MIT open source, self-hostable for free, and framework-agnostic via OpenTelemetry. Both offer tracing, datasets, evals, and monitoring.

Is Langfuse or LangSmith better for self-hosting?

Langfuse — it is MIT-licensed and self-hosts for free with docker compose, while LangSmith self-hosting needs an Enterprise agreement. If free self-hosting and data residency matter, Langfuse (or another open-source tool like Langprobe) is the stronger fit.

Is there an alternative to both LangSmith and Langfuse?

Yes — Langprobe is an open-source (Apache-2.0), self-hosted alternative that adds replay debugging and an agent-native MCP surface neither incumbent has.