Weights & Biases
The MLOps platform for experiment tracking, model registry, and LLM evaluation
Weights & Biases · Infrastructure
Launched 2018
Quick Answer
Weights & Biases is the mlops platform for experiment tracking, model registry, and llm evaluation, made by Weights & Biases. It offers a free tier with paid upgrades. Key uses: ML experiment tracking, LLM prompt management, Model versioning.
Last updated:
Users
1M+ users; 500K+ ML practitioners; OpenAI, NVIDIA, Samsung customers
Valuation
Acquired by CoreWeave for $1.7B (Jul 2025)
What is Weights & Biases?
Weights & Biases (W&B) is the leading MLOps platform for tracking machine learning experiments, visualising metrics, managing models in a registry, and evaluating LLM outputs. Used by teams at OpenAI, NVIDIA, Samsung, and thousands of other organisations to accelerate the ML development lifecycle.
What's new in Weights & Biases in 2026?
W&B Weave (LLM evaluation platform) GA 2024; acquired by CoreWeave for $1.7B (Jul 2025); Weave Traces for LLM observability; Integration with all major cloud AI providers; 1M+ users; W&B AI Academy
How much does Weights & Biases cost?
Free
$0/mo
- Unlimited experiments
- 100GB storage
- 1 private project
- Community support
Teams
$50/seat/mo
- Unlimited projects
- 1TB storage
- Priority support
- SSO
Enterprise
Custom
- Unlimited storage
- Self-hosted
- SLA
- Dedicated support
What can you do with Weights & Biases?
- ML experiment tracking
- LLM prompt management
- Model versioning
- Team collaboration on ML
- LLM fine-tuning
Pros
- Industry-standard experiment tracking
- Weave for LLM evaluation
- Integrates with every major ML framework
- Beautiful visualisations
- Free for individuals
Cons
- Can be expensive for large teams
- Learning curve
- Storage costs at scale
What are the best alternatives to Weights & Biases?
Compare Weights & Biases Head-to-Head
Frequently Asked Questions about Weights & Biases
How much does Weights & Biases cost?
Weights & Biases pricing: Free at $0/mo; Teams at $50/seat/mo; Enterprise at Custom.
Is Weights & Biases free?
Weights & Biases offers a free tier with limited usage. Paid plans unlock additional features.
What is Weights & Biases used for?
Weights & Biases is used for: ML experiment tracking, LLM prompt management, Model versioning, Team collaboration on ML, LLM fine-tuning.
What are the best alternatives to Weights & Biases?
Top alternatives to Weights & Biases include Databricks, Modal.
What platforms does Weights & Biases support?
Weights & Biases is available on: Web, Python SDK, CLI, Self-hosted (W&B Server).
Details
Platforms
Integrations
Ideal For
- ML engineers
- Data scientists
- AI research teams
- LLMOps engineers