Open-source agent tracing, evals and prompt management.
WebsiteProvisional comparison
Langfuse vs Arize Phoenix
Langfuse is provisional S-tier and Arize Phoenix is provisional A-tier on Agent Observability & Evals. Rankings are never for sale.
Full Agent Observability & Evals tier list
Open-source tracing and evaluation for LLM apps and agents.
Website| Field | Langfuse | Arize Phoenix |
|---|---|---|
| Tier | S · provisional | A · provisional |
| Why | Leading open-source observability (35k+ stars), self-hostable. | Strong OpenTelemetry-based open-source option. |
| Pricing | open-source / freemium cloud · starts at $29/mo | open-source / paid cloud · starts at $50/mo |
| GitHub stars | 35,875 | 11,858 |
| Last push | Oct 15, 2026 | Oct 15, 2026 |
| Last verified | Oct 15, 2026 | Oct 15, 2026 |