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
Category eval-observability eval-observability
License Proprietary MIT
Open source No Yes
Self-hostable No Yes
MCP support No No
Pricing paid freemium
Starting price Custom (enterprise) Self-host free; cloud tier
Models multi multi
Languages python python, typescript
GitHub stars — 29.8k
Last activity — 2026-06-25