Evaluation · Updated 2026-10-25
Arize Phoenix — what it is actually for
Arize Phoenix is an open-source observability and evaluation tool for LLM applications. It supports local tracing, experiments, and evaluation, with Phoenix Cloud and enterprise options.
Short answer: use Arize Phoenix when you need local tracing and debugging of llm apps. It is a open source + free cloud tier + subscription service from Arize AI; the official pricing source is linked below.
- Vendor
- Arize AI
- Category
- Evaluation
- Pricing model
- Open source + free cloud tier + subscription
- Free option
- Yes. The open-source project is free, and Phoenix Cloud has a free tier.
What Arize Phoenix is used for
- Local tracing and debugging of LLM apps
- Evaluation experiments and RAG analysis
- OpenTelemetry-based instrumentation
Source: official product page and official documentation.
Who Arize Phoenix is for
- Teams that want open-source plus OpenTelemetry
- Local debugging and RAG evaluation
- Cost-sensitive evaluation workflows
Source: official documentation.
Who it is not for
- Teams that need a fully managed enterprise suite from day one
- No-code users
Source: documented plans, limits, and deployment model on the official product page.
Pricing
- The open-source project is free to self-host.Source: phoenix.arize.com
- Phoenix Cloud free tier includes 25,000 spans per month, 10 issues, and 1 GB of data.Source: phoenix.arize.com
- The paid cloud tier is US$50 per month with 50,000 spans, 25 issues, and 10 GB; Enterprise pricing is custom.Source: phoenix.arize.com
The self-hosted open-source edition has no license fee. Cloud tiers meter spans, issues, and stored data.
Full pricing page: https://phoenix.arize.com/pricing/
Alternatives to Arize Phoenix
- LangSmith — Tracing, evaluation, and observability for LLM and agent applications.
- Braintrust — Evaluation, logging, and prompt playground for AI products.
- W&B Weave — Tracing and evaluation for LLM apps inside the Weights & Biases platform.
Official sources
Arize Phoenix FAQ
Is Arize Phoenix free?
Yes. The open-source edition is free to self-host, and Phoenix Cloud has a free tier with 25,000 spans per month.
Does Phoenix support OpenTelemetry?
Yes. Phoenix documents OpenTelemetry-based instrumentation for LLM applications.
What is included in the paid Phoenix tier?
The US$50/month tier includes 50,000 spans, 25 issues, and 10 GB of data according to the pricing page.