Arize AX vs Galileo
Both are observability & tracing tools. Here is how they actually differ on price, billing model and deployment.
Arize AX
The commercial cloud product from the makers of Phoenix. The upgrade from free Phoenix is not a tier change - it is a repricing onto per-span billing, and online monitoring is the feature that forces it.
Galileo
The best-funded evaluation-and-observability platform in this space, built around proprietary Luna eval models. Not to be confused with the Google-acquired text-to-UI tool of the same name. Real pricing is sales-led above $100/mo.
| Arize AX | Galileo | |
|---|---|---|
| Category | Observability & Tracing | Observability & Tracing |
| Our rating | 4/5 | 4/5 |
| Starting price | $50/mo | $100/mo |
| Billing meter | span | span |
| Free plan | Yes | Yes |
| Free self-hosting | No or paid tier only | No or paid tier only |
| Best for | Teams that outgrew self-hosted Phoenix and want the managed version without operating it, mixed ML and GenAI shops that need computer vision and model observability in the same platform, and regulated teams needing HIPAA. | Enterprise GenAI teams that have been burned by production hallucinations and want research-grade eval metrics plus guardrails, and can run a sales process |
Our verdict on Arize AX
Arize AX is the managed, production-grade half of a genuinely good two-product strategy, and the honest way to evaluate it is to understand what forces the move from free Phoenix. It is not scale, and it is not support. It is online monitoring. The open-source Phoenix build does not include online monitoring or online evaluations as part of its observability stack, so the moment you need to evaluate live production traffic rather than debug locally, you are buying AX. That is a defensible commercial line, and Arize is more upfront about it than most, but it means Phoenix is best understood as an excellent development and debugging tool rather than a complete production platform. AX itself is strong - genuinely mature ML and computer vision observability inherited from Arize's older business, online evals, and pricing that scales on spans rather than seats, which is unusually favourable for large teams. The catch is that per-span billing punishes agent workloads, and the jump from $50 a month to a reported median Enterprise spend near $60,000 a year is a cliff with nothing published in between.
Full Arize AX review →Our verdict on Galileo
Galileo is the best-funded and arguably most research-forward platform here, and the Luna eval models are a real bet on making evaluation cheap enough to run continuously. Two caveats. First, make sure you're evaluating this Galileo and not the design tool that shares the name - the pricing and reviews get conflated constantly. Second, above the $100 Pro tier everything is contact-sales, and self-host is Enterprise-only, so this is a platform you buy through a rep, not a card.
Full Galileo review →Frequently Asked Questions
What is the main difference between Arize AX and Galileo?
Arize AX: Teams that outgrew self-hosted Phoenix and want the managed version without operating it, mixed ML and GenAI shops that need computer vision and model observability in the same platform, and regulated teams needing HIPAA. Galileo: Enterprise GenAI teams that have been burned by production hallucinations and want research-grade eval metrics plus guardrails, and can run a sales process Both sit in Observability & Tracing, so the decision usually comes down to billing model and deployment rather than raw capability.
Which is cheaper, Arize AX or Galileo?
It depends entirely on your workload shape, because they meter differently - Arize AX bills on span and Galileo bills on span. Published starting prices are $50/mo and $100/mo respectively, but those numbers are not comparable until you apply them to the same traffic. Use our cost calculator to model both against your own request volume and span count.
Can I self-host Arize AX or Galileo?
Arize AX: No or paid tier only. Galileo: No or paid tier only. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.