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LangSmith vs Langfuse vs Helicone — LLM Observability Platform Comparison

Three platforms for monitoring, debugging, and evaluating LLM applications in production. LangSmith is LangChain's integrated solution, Langfuse is the most popular open-source alternative acquired by ClickHouse, and Helicone offers the simplest setup through a single-line proxy integration.

analyzed by Raşit Akyol March 29, 2026 updated April 16, 2026

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LangSmithLangfusewinnerHelicone

What Sets Them Apart

As LLM applications move into production, observability becomes critical for understanding performance, debugging failures, and ensuring output quality. LangSmith, Langfuse, and Helicone represent the three leading approaches to LLM observability, each with distinct integration patterns and strengths.

Tailwind, Bootstrap, and Bulma at a Glance

LangSmith is LangChain's native observability platform, providing the deepest integration with the LangChain and LangGraph ecosystem. It offers detailed tracing of every chain and agent execution step, dataset management for regression testing, prompt versioning, and automated evaluation with custom metrics. The annotation queue enables human feedback collection. LangSmith works with any LLM framework via SDK, but shines brightest for LangChain users. Free tier includes 5K traces/month, with Plus at $39/seat/month.

Langfuse is the most popular open-source LLM observability platform with 21K+ GitHub stars, recently acquired by ClickHouse. It provides framework-agnostic tracing, prompt management with versioning, dataset-based evaluation, user feedback collection, and detailed cost tracking. The key advantage is deployment flexibility — self-host via Docker for complete data ownership, or use the managed cloud. Native integrations cover LangChain, LlamaIndex, OpenAI SDK, and Vercel AI SDK. Free open-source with cloud Pro from $59/month.

Helicone takes the simplest integration approach — change your API base URL to route LLM requests through Helicone's proxy, and instantly get logging, cost tracking, latency monitoring, caching, and rate limiting. No SDK installation or code changes required beyond the URL swap. This proxy-based approach works with any LLM provider across 300+ models. Has processed over 2 billion interactions. Free tier includes 100K requests/month.

Customization, Learning Curve, and Performance

The choice depends on your priorities. LangSmith for deep LangChain integration and the most comprehensive evaluation features. Langfuse for open-source flexibility, self-hosting, and strong framework-agnostic observability. Helicone for the fastest setup with immediate value through proxy-based monitoring. Many teams start with Helicone for quick wins and add LangSmith or Langfuse for deeper evaluation workflows.

Ecosystem and Production Readiness

The Bottom Line

Quick Comparison

LangSmith

Pricing
Free tier (5K traces/mo) / Plus $39/seat/mo / Enterprise custom
Pricing Model
Freemium
Platforms
Web, Python SDK, JavaScript SDK, API
Open Source
No
Telemetry
Clean
Status
Active
Editorial Pick
—
Last Verified
—
Description
LangSmith is LangChain's platform for debugging, testing, evaluating, and monitoring LLM applications in production. Provides detailed tracing of every step in LLM chains and agent workflows, dataset management for regression testing, prompt versioning, and automated evaluation with custom metrics. Features an annotation queue for human feedback, online monitoring dashboards, and integration with LangChain, LangGraph, and any LLM framework via the Python/JS SDK. Essential for production LLM ops.

Langfusewinner

Pricing
Hobby free / Core from $29/mo / Pro from $199/mo
Pricing Model
Open Source
Platforms
Web, Self-hosted, Docker, Python, JS/TS SDK
Open Source
Yes
Telemetry
Clean
Status
Active
Editorial Pick
—
Last Verified
—
Description
Langfuse is an open-source LLM engineering platform with 29K+ GitHub stars for tracing, evaluating, and monitoring AI applications. Acquired by ClickHouse, it provides detailed traces of LLM calls, prompt management with versioning, dataset-based evaluation, user feedback collection, and cost tracking. Framework-agnostic with native integrations for LangChain, LlamaIndex, OpenAI SDK, and Vercel AI SDK. Offers both self-hosted deployment and a managed cloud service.

Helicone

Pricing
Hobby free: 10,000 requests; Pro $79/mo; Team $799/mo; Enterprise custom.
Pricing Model
Freemium
Platforms
Web, Proxy API, Self-hosted, Docker
Open Source
Yes
Telemetry
Clean
Status
Active
Editorial Pick
—
Last Verified
—
Description
Helicone is an open-source LLM observability and AI gateway platform with proxy-based request logging, cost tracking, latency monitoring, caching, rate limits, user analytics, prompt tools, and HQL. It supports OpenAI, Anthropic, Azure, LiteLLM, Anyscale, Together AI, and OpenRouter integrations, and now presents itself as part of Mintlify while continuing managed and self-hosted gateway/observability workflows.

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