Arthur vs Weights & Biases Weave

Arthur is an AI performance and safety platform founded in 2018 and headquartered in New York City. The platform provides monitoring, explainability, and bias detection for production ML, plus Arthur Shield for LLM firewall and red-teaming. Arthur raised a $42M Series B in September 2022 led by Acrew Capital and Greycroft, bringing total funding to approximately $56M.

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.