Arize AI vs Arthur

Both compete in Observability & Monitoring. Arize AI positions itself as “AI observability and evaluation platform for ML models, LLM apps, and agents”, while Arthurleads with “AI performance, evaluation, and governance platform for ML, generative, and agentic systems”. The table below compares what each publishes.

Where Arize AI pulls ahead

Publishes support for GDPR, which Arthur does not. AI engineering and ML teams wanting unified LLM/agent observability and evaluation with an open-source (Phoenix) on-ramp to enterprise-scale monitoring

Where Arthur pulls ahead

Publishes support for NIST AI RMF, EU AI Act, which Arize AI does not. Enterprises operationalizing generative and agentic AI that want flexible deployment (SaaS, VPC, on-prem) and an open-source evaluation engine alongside governance controls.

Both map to SOC 2, HIPAA, so framework coverage alone will not separate them — the decision usually comes down to who operates the tool and how it fits your existing stack.

	Arize AI	Arthur
Positioning	AI observability and evaluation platform for ML models, LLM apps, and agents	AI performance, evaluation, and governance platform for ML, generative, and agentic systems
Category	Observability & Monitoring	Observability & Monitoring
Frameworks	SOC 2, HIPAA, GDPR	NIST AI RMF, EU AI Act, SOC 2, HIPAA
Deployment	SaaS, Cloud, On-prem, Open-source, API	SaaS, Cloud, On-prem, Open-source, API
Built for	Data Science / ML, Risk, Compliance	Data Science / ML, Compliance, Risk, Security
Founded	2020	2018
Headquarters	Berkeley, California, USA	New York, New York, USA
Ownership	Private, independent, venture-backed (as of mid-2026)	Private, independent; venture-backed
Funding	~$135M total raised across 5 rounds, including a $70M Series C in February 2025 led by Adams Street Partners; earlier $38M Series B (2022) led by TCV	Approximately $63M total across three rounds; $42M Series B (2022) led by Acrew Capital and Greycroft, with Index Ventures and Work-Bench. No publicly reported round since.
Pricing	Free open-source (Phoenix); commercial tiers with free/self-serve entry and enterprise plans (usage/seat-based, custom pricing)	Self-serve SaaS tier plus enterprise subscription for VPC/on-prem; open-source Arthur Engine available free
Key capabilities	End-to-end agent and LLM tracing Evaluation framework (span/trace/session evals, LLM-as-judge) Drift and performance monitoring Embedding and data quality analysis Bias/fairness monitoring Prompt testing and iteration	Pre-production, runtime, and production evaluations Real-time guardrails (prompt injection, PII, toxicity) Hallucination and groundedness detection Agent trace visualization and tool-selection metrics Drift and performance monitoring for classical ML Open-source Arthur Engine
Integrations	OpenAI, Anthropic, Google, Amazon Bedrock, LangChain, LangGraph, LlamaIndex, CrewAI, DSPy, OpenTelemetry / OpenInference	OpenAI, Anthropic Claude, Meta Llama, Google Gemini, Together.ai, CrewAI, AutoGen, smolagents, Slack, Jira
Notable customers	Reddit, DoorDash, Instacart, Uber, Spotify, PagerDuty, Booking.com	None published
Best for	AI engineering and ML teams wanting unified LLM/agent observability and evaluation with an open-source (Phoenix) on-ramp to enterprise-scale monitoring	Enterprises operationalizing generative and agentic AI that want flexible deployment (SaaS, VPC, on-prem) and an open-source evaluation engine alongside governance controls.
Limitations	Positioned as an observability and evaluation layer rather than a full GRC/policy-enforcement governance suite; enterprise features and depth may require the paid platform beyond open-source Phoenix, and the fast-evolving agent tooling can shift.	Named enterprise references are limited publicly; funding has not advanced past its 2022 Series B, and the rapid pivot toward agentic AI means several governance features are relatively new.

Which should you shortlist?

Choose Arize AI if aI engineering and ML teams wanting unified LLM/agent observability and evaluation with an open-source (Phoenix) on-ramp to enterprise-scale monitoring

Choose Arthur if enterprises operationalizing generative and agentic AI that want flexible deployment (SaaS, VPC, on-prem) and an open-source evaluation engine alongside governance controls.

Neither is a substitute for a governance program. Whichever you pick, you still need people who can define the policies the tool enforces.

Full Arize AI profile →Full Arthur profile →

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