Arize Phoenix vs Langfuse
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
AI tool · Open source
An open-source tool for tracing, evaluating and experimenting with LLM and agent applications, built on OpenTelemetry.
AI tool · Open source
An open-source LLM engineering platform for tracing, prompt management, evaluations and cost tracking.
The short answer
Choose Arize Phoenix if you need…
- Local debugging of LLM traces
- OpenTelemetry-based stacks
Choose Langfuse if you need…
- Tracing LLM apps in production
- Self-hosted prompt management
Side-by-side
| Arize Phoenix | Langfuse | |
|---|---|---|
| Type | Prompting · Evaluation & observability | Prompting · Evaluation & observability |
| Price | Open source | Open source |
| Platforms | Self-hosted, Web, API | Web, Self-hosted, API |
| Works with | LangChain, LlamaIndex, OpenAI | LangChain, OpenAI, LlamaIndex |
| Hands-on tested by us | Not yet | Not yet |
| Last checked | 2026-10-29 | 2026-10-29 |
What each one is
Arize Phoenix
An open-source tool for tracing, evaluating and experimenting with LLM and agent applications, built on OpenTelemetry. Standards-based and free to run locally. Enterprise features live in Arize's paid platform.
Langfuse
An open-source LLM engineering platform for tracing, prompt management, evaluations and cost tracking. A popular, well-documented default for observability. Self-hosting at scale needs some operational effort.
Best for
Arize Phoenix
- Local debugging of LLM traces
- OpenTelemetry-based stacks
Langfuse
- Tracing LLM apps in production
- Self-hosted prompt management
Strengths
Arize Phoenix
- OpenTelemetry tracing
- LLM-as-judge evals
- Prompt playground
- Datasets and experiments
Langfuse
- Traces and spans for LLM calls
- Prompt management with versions
- Evals and datasets
- Cost and latency dashboards
Frequently asked questions
What is the difference between Arize Phoenix and Langfuse?
Arize Phoenix: An open-source tool for tracing, evaluating and experimenting with LLM and agent applications, built on OpenTelemetry. Langfuse: An open-source LLM engineering platform for tracing, prompt management, evaluations and cost tracking. Arize Phoenix suits local debugging of llm traces, while Langfuse suits tracing llm apps in production.
Are Arize Phoenix and Langfuse free?
Arize Phoenix: Open source. Langfuse: Open source.
What are other alternatives to Arize Phoenix and Langfuse?
Other options people compare them with include Confident AI (DeepEval), LangSmith, Opik, promptfoo, Braintrust.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.