LLM Eval & Observabilityfree

Arize Phoenix

Fully open-source, self-hostable with zero setup via `uvx` (pip/conda also supported)

Visit Arize Phoenix

What Arize Phoenix does

  • Fully open-source, self-hostable with zero setup via `uvx` (pip/conda also supported)
  • Combines tracing, evals, datasets, experiments and prompt playground in one local-first tool
  • AI engineering agent (PXI) built in for automated troubleshooting of traces

Arize Phoenix — straight answers

What is Arize Phoenix?

Arize Phoenix is listed under LLM Eval & Observability, in the AI Models & Local Execution category on Flocci AI Tools. Fully open-source, self-hostable with zero setup via `uvx` (pip/conda also supported). It is free, with no paid plan attached, and it lives at phoenix.arize.com.

Is Arize Phoenix free?

Arize Phoenix is listed as fully free — there is no paid tier attached to it in the catalog. That makes it one of the 396 entries on Flocci AI Tools with no upgrade path built in.

Can I use Arize Phoenix in a browser, or is there an app?

Arize Phoenix works in a normal browser tab with no install. It is available on self-hosting, the web and an API.

What can Arize Phoenix do?

Arize Phoenix does 3 things the catalog singles out: Fully open-source, self-hostable with zero setup via `uvx` (pip/conda also supported); combines tracing, evals, datasets, experiments and prompt playground in one local-first tool; ai engineering agent (pxi) built in for automated troubleshooting of traces.

What is the best free alternative to Arize Phoenix?

Google Stax is the closest free alternative: it sits in the same LLM Eval & Observability sub-category and is free. Laminar, DeepEval and EleutherAI LM Evaluation Harness also start free. The full list is on the alternatives page.

See the full list →

Arize Phoenix alternatives

Compare all alternatives →

Langfuse

LLM Eval & Observability
freemium
  • Fully open-source and self-hostable for free via Docker Compose/Kubernetes, not just a hosted SaaS
  • Hobby cloud plan is free with no credit card, 50k observability units/month
  • Combines tracing, prompt management, evals and datasets in one open platform
Visit

Braintrust

LLM Eval & Observability
freemium
  • Free Starter plan ships model credits and scored evals with no card required
  • Unlimited users/projects/datasets/playgrounds even on the free tier
  • Built-in playground for side-by-side prompt/model comparison against production traces
Visit

Promptfoo

LLM Eval & Observability
freemium
  • Open-source CLI/library for evaluating prompts, models and RAG pipelines side by side, runs in CI
  • Automated red-teaming to surface prompt injection, jailbreak and data-leak vulnerabilities
  • 300,000+ user community with an enterprise tier for teams needing hosted guardrails
Visit

W&B Weave

LLM Eval & Observability
freemium
  • Agent-native tracing model with sessions, steps, tools and sub-agents as first-class concepts (not generic spans)
  • Pre-built safety/quality scorers for toxicity, bias, PII and hallucination detection out of the box
  • Built on Weights & Biases' existing ML-experiment infrastructure, useful for teams already on W&B
Visit

Google Stax

LLM Eval & Observability
freeNew
  • Build evals with human raters or LLM autoraters on your own data
  • Compare models and prompts on quality, latency and token cost
  • Prebuilt and custom evaluators
Visit

DeepEval

LLM Eval & Observability
freeNew
  • Open-source LLM evaluation framework with pytest-style tests and 50+ metrics
  • RAG, agent and conversational metrics; red-teaming module
  • Apache-2.0; optional Confident AI cloud has a free tier
Visit

Head-to-head comparisons

Arize Phoenix vs LangfuseArize Phoenix vs BraintrustArize Phoenix vs PromptfooArize Phoenix vs W&B WeaveArize Phoenix vs Google StaxArize Phoenix vs DeepEval