Weights & Biases
ML experiment tracking and model management platform with rich visualisations.
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
Maintenance
Learning
Licence
// 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
| Tool | Choose it when |
|---|---|
| MLflow | You want open-source, self-hostable lifecycle tracking. |
| Braintrust | Your focus is LLM evals with datasets and a UI. |
| LangSmith | You 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
Install and log in to W&B
Instrument training/eval with SDK calls
Log params, metrics and artifacts
Compare runs in the managed UI
Use Weave for LLM-app evaluation
Gate CI on logged metrics
// RELATED QA.CODES RESOURCES
Cheat sheets
Glossary