What is the best free alternative to Arize Phoenix?
Google Stax is the closest free alternative to Arize Phoenix: same LLM Eval & Observability sub-category, and it is free. Build evals with human raters or LLM autoraters on your own data
Best free Arize Phoenix alternatives
Looking for a free alternative to Arize Phoenix? Here are 9 llm eval & observability worth trying — 9 with a free tier. Arize Phoenix itself is free.
| Tool | Arize Phoenix (you searched) | Google Stax | Laminar | Langfuse |
|---|---|---|---|---|
| Pricing | free | free | free | freemium |
| Best for | Fully open-source, self-hostable with zero setup via `uvx` (pip/conda also supported) | Build evals with human raters or LLM autoraters on your own data | Open-source observability and evals platform for AI agents (Apache-2.0) | Fully open-source and self-hostable for free via Docker Compose/Kubernetes, not just a hosted SaaS |
| Visit | Open ↗ | Open ↗ | Open ↗ | Open ↗ |
Arize Phoenix alternatives — straight answers
Are there free Arize Phoenix alternatives?
Yes — 9 of the 9 alternatives listed here are free or freemium: Google Stax, Laminar, Langfuse, Braintrust, Promptfoo. None of them are paid-only.
Is Arize Phoenix free?
Arize Phoenix is free. There is no paid plan attached to it in the catalog.
How were these Arize Phoenix alternatives chosen?
They are the other tools in LLM Eval & Observability, then the rest of AI Models & Local Execution, ordered free tiers first and capped at 9. There is no sponsorship and no paid placement in that ordering — only the pricing tier decides.
All Arize Phoenix alternatives
Browse LLM Eval & Observability →✦ WhyA Arize Phoenix alternative — Build evals with human raters or LLM autoraters on your own data.
- 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
✦ WhyA Arize Phoenix alternative — Open-source observability and evals platform for AI agents (Apache-2.0).
- Open-source observability and evals platform for AI agents (Apache-2.0)
- Traces, session replay for browser agents and evaluations
- Self-hostable
Langfuse
LLM Eval & Observability
✦ WhyA Arize Phoenix alternative — Fully open-source and self-hostable for free via Docker Compose/Kubernetes, not just a hosted SaaS.
- 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
Braintrust
LLM Eval & Observability
✦ WhyA Arize Phoenix alternative — Free Starter plan ships model credits and scored evals with no card required.
- 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
Promptfoo
LLM Eval & Observability
✦ WhyA Arize Phoenix alternative — Open-source CLI/library for evaluating prompts, models and RAG pipelines side by side, runs in CI.
- 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
W&B Weave
LLM Eval & Observability
✦ WhyA Arize Phoenix alternative — Agent-native tracing model with sessions, steps, tools and sub-agents as first-class concepts (not generic spans).
- 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
✦ WhyA Arize Phoenix alternative — Open-source LLM tracing, evaluation and prompt-optimization platform (Apache-2.0).
- Open-source LLM tracing, evaluation and prompt-optimization platform (Apache-2.0)
- Free cloud plan with 25k spans a month, up to 10 team members and 60-day retention
- Self-host with no limits
✦ WhyA Arize Phoenix alternative — Tracing, evaluation datasets and prompt playground for LLM apps and agents.
- Tracing, evaluation datasets and prompt playground for LLM apps and agents
- Developer plan is free with 5k base traces a month and one seat
- Framework-agnostic, works beyond LangChain
✦ WhyA Arize Phoenix alternative — Open-source LLM evaluation framework with pytest-style tests and 50+ metrics.
- 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