Weights & Biases

Experiment tracking and model monitoring for ML teams

AI Models & PlatformsFree planOverseasβ˜…β˜…β˜…β˜…β˜† 4.0

What is Weights & Biases?

Weights & Biases, usually called W&B, is a platform for tracking machine-learning experiments. A few lines of code log metrics, hyperparameters, system usage and artifacts from a training run, and everything appears in a shared dashboard where runs can be compared and filtered. It also covers hyperparameter sweeps, dataset and model versioning, and reporting. The differentiator is reproducibility: teams use it as the record of what was actually tried, which is hard to reconstruct from terminal logs and notebooks after the fact.

Last updated: 2026-09-20. This site only provides an index; for exact features, pricing, and licensing, see the official website.

Key features

  • Live metric charts with run comparison and filtering
  • Hyperparameter sweeps with early stopping strategies
  • Artifact versioning for datasets and model checkpoints
  • Reports that embed live charts and result tables
  • Integrations with PyTorch, TensorFlow, Keras and Hugging Face
  • LLM tracing and evaluation tooling for prompt workflows

Pros & cons

Strengths

  • Very small code change to start logging a training run
  • Makes comparing dozens of experiments practical
  • Free for personal projects and academic research

Watch out for

  • Long-running projects can accumulate significant cost
  • Logged data lives in a third-party service by default
  • Most teams use only a fraction of the available features

Best for & use cases

experiment tracking, hyperparameter search, model versioning, ml team reporting

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FAQ

What does experiment tracking actually record?

Metrics over time, hyperparameters, code version, system resource use and output artifacts for each run. The value is being able to compare runs and reproduce a result weeks later.

Is there a free plan?

Yes, W&B is free for personal projects and academic research, with limits on storage and collaboration features. Team and enterprise plans bill per seat and raise those limits.

Does it work with any framework?

It integrates with PyTorch, TensorFlow, Keras, scikit-learn and many others, and you can log manually from plain Python. Adding it to an existing training script is usually a few lines.