Langfuse vs Helicone

Langfuse and Helicone are the two leading LLM observability platforms, taking fundamentally different approaches — SDK-based tracing versus proxy-based logging.

Overview

Langfuse is an open-source LLM observability platform offering detailed tracing, evaluation frameworks, prompt management, and cost analytics through SDK integration. Helicone is a one-line proxy that logs, monitors, caches, and rate-limits all LLM API calls by simply changing your base URL — no code changes needed.

Key Differences

Integration approach: Langfuse requires adding SDK calls (decorators, wrappers) to your code. Helicone just needs a base URL change — truly zero code changes. Tracing depth: Langfuse provides nested traces with spans, generations, and events — showing exactly how your AI pipeline executed. Helicone logs request/response pairs without internal pipeline visibility. Caching: Helicone offers built-in semantic caching that can reduce costs 30-50%. Langfuse does not include caching — it's an observability tool, not a proxy. Self-hosting: Langfuse is MIT-licensed and self-hostable with full features. Helicone's self-hosting is more complex due to its proxy architecture. Evaluation: Langfuse includes a comprehensive evaluation framework with custom scorers, human annotation, and dataset management. Helicone focuses on logging and analytics without built-in evaluation. Gateway features: Helicone doubles as an LLM gateway with retries, fallbacks, and rate limiting. Langfuse is purely observability.

Feature Matrix

| Feature | Langfuse | Helicone |

|---------|----------|----------|

| Setup complexity | SDK integration | URL change |

| Nested tracing | Yes | No |

| Caching | No | Yes (semantic) |

| Evaluation framework | Yes | No |

| Gateway features | No | Yes (retries, fallbacks) |

| Self-hosting | Easy (MIT) | Complex |

| Prompt management | Yes | No |

Verdict

Choose Langfuse if you need deep tracing, evaluation frameworks, and prompt management for a complex AI application. Choose Helicone if you want instant observability with zero code changes, built-in caching for cost savings, and gateway features like retries and fallbacks.