Fiddler AI vs Weights & Biases Weave

Fiddler AI is an AI observability and security platform founded in 2018 and headquartered in Palo Alto, California, by Krishna Gade, Amit Paka, and Manoj Cheenath. Fiddler focuses on production monitoring — drift, performance, fairness, explainability — and has extended into LLM observability and security for compound and agentic AI systems. Fiddler raised a $30M Series C in January 2026, bringing total funding to $100M.

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.