Arize AI

Arize AI is an observability and evaluation company whose platform helps AI teams trace what agents do, measure quality and improve them over time. It offers two paths: Arize AX, a managed platform with an in-app AI engineering agent, and Phoenix, an open-source tool for tracing and evals that you run yourself. Its tracing builds on OpenInference, an open semantic convention on top of OpenTelemetry, so instrumentation is not tied to one vendor.

What is Arize AI used for?

Arize is used to debug and monitor LLM applications and agents from development through production. Typical uses include:

• Tracing agent runs with token, latency and cost tracking, including multimodal steps
• Running online evals on live traffic and offline evals on datasets
• Comparing prompts and models in playgrounds and experiments
• Setting up human annotation and labeling queues
• Letting the Alyx agent run evals, find issues and suggest fixes
• Running Phoenix locally during development without a cloud account

Who Arize AI is best for

Arize suits ML engineers, AI engineers and data science teams at companies running AI in production, including large enterprises that need SOC 2, ISO 27001, HIPAA and PCI DSS coverage. Teams that want an open-source path can start on Phoenix and move to AX later. Individuals experimenting with a single prompt may find a full observability platform more than they need.

Arize AI pricing

As of October 2026, Arize AX Free costs $0 with no credit card and includes 25,000 trace spans and 1GB of ingestion a month, 15 days of retention, 10 Signal issues and unlimited users and evals. AX Pro costs $50 per month with 50,000 spans, 10GB of ingestion, 30 days of retention, 25 Signal issues and email support. AX Enterprise is custom priced through a demo and adds custom limits, custom dashboards and monitors, SSO, audit logs, bring-your-own-key AI providers and SaaS or self-hosted deployment. Phoenix, the open-source tool, is free to run yourself. Startup pricing is also mentioned without details.

Limitations to keep in mind

• Span limits on Free and Pro are low for busy production agents
• Custom dashboards, metrics and monitors are Enterprise-only
• Phoenix and AX are separate products, so moving between them takes some setup
• It observes and evaluates agents but does not build them

Arize AI vs alternatives

LangChain's own tracing and evaluation product is convenient if your agents already run on LangChain, though it is tied more closely to that ecosystem. LlamaIndex focuses on building retrieval and data pipelines and relies on integrations such as Phoenix for deeper observability. OpenAI Playground is useful for quick prompt checks with OpenAI models but does not monitor production systems. Arize wins when you want standards-based tracing, strong evals, an open-source option and enterprise compliance in one vendor.

Tips for getting started with Arize AI

Start with Phoenix locally to instrument your app and see traces in minutes without sign-up. Add session IDs so you can evaluate whole conversations, not just single calls. Move to AX when you need shared dashboards, Alyx or longer retention. Watch span counts in the first weeks, since agents with many tool calls use spans quickly.

Arize AI FAQ

Is Arize AI free?

Yes. Arize AX has a free plan with 25,000 trace spans per month, and Phoenix is free and open source. AX Pro costs $50 per month.

What is the difference between Arize AX and Phoenix?

Arize AX is the managed platform with features like Alyx, Signal and enterprise controls, while Phoenix is Arize's open-source tool for tracing and evals that runs locally or self-hosted.

Does Arize AI support OpenTelemetry?

Yes. Arize AX provides OpenTelemetry-compliant observability, and its tracing is based on OpenInference, an open-source convention built on OpenTelemetry.

Is Arize AI safe to use with company data?

Arize lists SOC 2, ISO 27001, PCI DSS, HIPAA and GDPR certifications, and AX Enterprise offers self-hosted deployment for stricter requirements.