A agentindex
Comparison

Fiddler vs Langfuse

A like-for-like, spec-level comparison. Both entries are verified against their docs and repo.

Fiddler

AI observability and governance for enterprise.

  • + Strong governance and compliance story
  • + Good for regulated enterprise
  • − Enterprise-priced
  • − Heavier than dev-focused tools

Langfuse

The most-used open-source LLM observability tool.

  • + Open source and self-hostable
  • + Framework-agnostic via OpenTelemetry
  • − Self-hosting ClickHouse is operational work
  • − Eval features trail dedicated eval tools
Spec Fiddler Langfuse
Role Observability Observability
Tags observability, guardrails, persona-platform-engineer observability, evaluation, prompt-management, persona-data-scientist, persona-platform-engineer
License Proprietary MIT
Open source No Yes
Self-hostable No Yes
MCP support No No
Pricing paid freemium
Price Custom Free tier
Usage cost No model cost No model cost
Models multi multi
Languages python python, typescript
GitHub stars — 30.4k
Last activity — 2026-07-03