Arize AI vs Weights & Biases Weave

Arize AI is an LLM observability and evaluation platform designed for enterprises running AI agents and LLM applications at scale. Its flagship product, Arize AX, provides real-time monitoring, agent tracing, prompt management, online evaluations using LLM-as-a-Judge, and drift detection across NLP, computer vision, and multimodal models. The company also maintains Arize Phoenix, a widely adopted open-source AI observability library built on OpenTelemetry/OpenInference standards.

Weights & Biases (W&B) is a San Francisco-based MLOps and LLMOps platform founded in 2017. Weave is W&B's product layer purpose-built for LLM observability, evaluation, and governance. It provides automatic tracing of LLM calls (inputs, outputs, latency, cost), evaluation pipelines with human and automated scoring, dataset versioning, and guardrails to block prompt attacks and harmful outputs. Weave integrates with major LLM providers including OpenAI, Anthropic, Google Gemini, and frameworks such as LangChain and LlamaIndex. For AI compliance, W&B runs EU AI Act-focused webinar series demonstrating how Weave can generate compliance dossiers for high-risk AI systems, providing audit trails and evidence generation. The platform holds SOC 2 Type II certification. Enterprise tier includes SSO, RBAC, and private cloud deployment. W&B has raised $305M total and was valued at $1.25B in 2023.