Weights & Biases

Weights & Biases (W&B) is an MLOps and LLMOps platform that gives ML and AI teams experiment tracking, model and dataset versioning, hyperparameter optimization, and a system of record for training models and developing GenAI applications. It pairs W&B Models for the ML lifecycle with W&B Weave for tracing and evaluating LLM and agent applications.

Category

Developer Tools

Pricing

Freemium, Subscription, Usage-based, Contact for pricing

Target Market

Data Scientists, ML Engineers, AI Researchers, Enterprise Developers, CTOs

Founded

2017

Headquarters

San Francisco, California, USA

Customers

1,000+ companies and over 1 million AI engineers/practitioners

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  Experiment Tracking

  Logs metrics, hyperparameters, code, model weights, and sample predictions so training runs can be visualized, compared, and reproduced.

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  Sweeps (Hyperparameter Optimization)

  Automates hyperparameter search across runs to find optimal model configurations.

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  Model & Artifact Registry

  Versions and manages datasets, models, and ML pipelines with lineage tracking for governance and reproducibility.

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  W&B Weave

  Provides tracing, evaluations, guardrails, and production monitoring for LLM and agent applications.

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  Reports

  Creates interactive, shareable dashboards to document and collaborate on ML insights across a team.

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  Serverless Inference & Training

  Offers hosted open-source LLMs plus serverless fine-tuning with RL and SFT, powered by CoreWeave infrastructure.

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  Foundation model training

  AI labs use W&B Models to track large-scale pre-training and fine-tuning runs and debug infrastructure issues.

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  GenAI application development

  Teams use W&B Weave to trace, evaluate, and monitor LLM and agent applications from experimentation to production.

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  Hyperparameter tuning at scale

  Data scientists run Sweeps to systematically optimize model performance across many configurations.

Free tier and a self-hosted Personal tier are $0; Pro starts around $60/mo with usage-based overages for storage ($0.03/GB) and Weave data ingestion ($0.10/MB). Enterprise and Advanced (self-hosted) tiers are custom-priced. Free Pro-tier access is available for qualifying academics.