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Weights & Biases

Freemium

ML experiment tracking and model management platform with rich visualisations.

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Pricing

Freemium

Type

Automation

Languages

Python, JavaScript

// VERDICT

Reach for Weights & Biases when you want polished, managed experiment tracking and visualisation for ML, plus LLM evaluation via Weave. Skip it when you need fully open-source self-hosting (MLflow) or just lightweight prompt evals.

Best for

A managed platform for ML experiment tracking, visualisation and collaboration - logging runs, comparing experiments, and (via Weave) evaluating LLM apps, with a rich UI.

Avoid when

You want a fully open-source self-hosted tool, or only lightweight prompt evals.

CI/CD fit

SDK logging · managed platform · CI integration

Languages

Python · JavaScript

Team fit

ML/data-science teams · Research teams · Teams wanting rich experiment UIs

Setup

Easy

Maintenance

Low

Learning

Intermediate

Licence

Freemium

// BEST FOR

  • Tracking and visualising ML experiments richly
  • Comparing runs and hyperparameters
  • Collaboration and shareable dashboards
  • LLM app evaluation via Weave
  • Logging from training/eval with a few SDK calls
  • Reproducible, comparable experiments

// AVOID WHEN

  • You need fully open-source self-hosting (MLflow)
  • Only lightweight LLM prompt evals are needed
  • You can't send data to a managed service
  • Minimal/no-platform is preferred
  • You're not tracking experiments
  • On-prem-only is mandatory

// QUICK START

pip install wandb && wandb login
# wandb.init(); wandb.log({metric: value}) from training/eval
# use Weave for LLM-app evaluation

// ALTERNATIVES TO CONSIDER

ToolChoose it when
MLflowYou want open-source, self-hostable lifecycle tracking.
BraintrustYour focus is LLM evals with datasets and a UI.
LangSmithYou want LLM tracing + eval specifically.

// FEATURES

  • Experiment tracking for metrics, hyperparameters, and artifacts
  • Sweeps for automated hyperparameter search
  • Reports for shareable, narrative analyses of runs
  • Model registry with lineage and approval workflows
  • Weave for evaluating and tracing LLM applications

// PROS

  • Excellent visualisations and run-comparison UI
  • Lightweight integration — a few lines per training script
  • Free tier sufficient for individuals and small teams
  • Strong adoption across ML research and industry

// CONS

  • Hosted service — sensitive workloads need self-managed deployment
  • Cost scales quickly with team size and storage
  • Some advanced features locked behind enterprise plans

// EXAMPLE QA WORKFLOW

  1. Install and log in to W&B

  2. Instrument training/eval with SDK calls

  3. Log params, metrics and artifacts

  4. Compare runs in the managed UI

  5. Use Weave for LLM-app evaluation

  6. Gate CI on logged metrics

// RELATED QA.CODES RESOURCES