Direct answer
What is Weights & Biases?
Weights & Biases provides developer tooling for machine learning and generative AI, covering experiment tracking, hyperparameter optimization, model registry, and LLM application evaluation via Weave.
Weights & Biases (W&B) operates as an AI developer platform spanning the machine learning lifecycle from initial experimentation to production agent monitoring. The platform is divided into two primary environments: W&B Models and W&B Weave. W&B Models focuses on deep learning pipelines, providing lightweight experiment logging, hyperparameter sweeps, interactive data visualization via W&B Tables, and model and dataset versioning with W&B Artifacts. W&B Weave targets generative AI, enabling developers to capture traces across LLM calls, assess prompt chains with automated or LLM-as-a-judge scorers, run evaluations, and monitor agent steps in production. W&B supports cloud-hosted SaaS deployment, dedicated single-tenant configurations, and self-hosted instances running locally or within customer-managed infrastructure via Docker and Python. Security controls include ISO/IEC 27001, 27017, and 27018 certifications, SOC 2 Type II compliance, and support for HIPAA and single sign-on.
Bridges traditional machine learning experiment tracking and model registries with LLM observability, tracing, and automated evaluations in a single unified platform.
Product capabilities
Key features
Experiment Tracking
Log hyperparameters, system metrics, loss curves, and code states across training runs using standard Python libraries.
W&B Weave for GenAI
Trace LLM calls, document retrieval steps, prompt inputs, and outputs with automated evaluation and online monitoring.
Hyperparameter Sweeps
Automate model hyperparameter search across multiple machines and visualize performance trade-offs.
Artifact and Model Registry
Track dataset and model versioning, maintain complete asset lineage, and manage staging for production models.
Collaborative Reports and Tables
Explore high-dimensional datasets interactively with W&B Tables and produce dynamic collaborative dashboards with W&B Reports.
Serverless Training and Inference
Fine-tune LLMs with serverless reinforcement learning or supervised fine-tuning, and run serverless inference across supported open-weight models.
Workflow
How Weights & Biases works
- Install the Python library using pip and initialize a project run with wandb.init() or weave.init().
- Instrument your training loop or LLM calls using decorators or framework callbacks to log metrics, hyperparameters, or execution traces.
- Inspect runs, evaluate models, and compare experiments collaboratively through the web interface or iOS mobile app.
Practical fit
Who should use Weights & Biases?
Deep Learning Experiment Management
Compare metrics, loss curves, and model checkpoints across distributed training jobs in frameworks like PyTorch and TensorFlow.
LLM Application Tracing and Evaluation
Inspect multi-step AI agent workflows, monitor token latency and cost, and score prompt outputs against evaluation datasets using Weave.
Dataset and Model Governance
Maintain reproducible audit trails of training datasets, preprocessing scripts, model weights, and deployment versions.
Editorial assessment
Pros and limitations
Where it is strong
- Broad ecosystem support covering PyTorch, Hugging Face, Lightning, TensorFlow, LangChain, and LlamaIndex
- Dual focus accommodating both core deep learning workflows and generative AI agent observability
- Flexible deployment choices including managed cloud, dedicated environments, and self-hosted Docker servers
- Free plans available for individual developers, self-hosters, and accredited academic research projects
Where to be careful
- Pro tier is restricted to organizations with fewer than 50 employees, requiring larger teams to negotiate Enterprise plans
- Usage beyond monthly quotas incurs variable fees for Weave data ingestion ($0.10/MB) and storage ($0.03/GB)
- Requires code instrumentation via Python SDK rather than visual or no-code configuration
Commercial context
Weights & Biases pricing
At the review date (September 2026), Weights & Biases provides a free tier for individual developers, an academic tier for non-profit research, and a Pro plan starting at $60 per month billed monthly for teams under 50 employees. Storage beyond quotas is billed at $0.03 per GB, with additional Weave data ingestion at $0.10 per MB. Enterprise plans require custom agreements. Check the official pricing page for updates.
| Plan | Price | What it includes |
|---|---|---|
| Free (Cloud-hosted) | $0 / monthly | |
| Pro (Cloud-hosted) | $60 / monthly | |
| Enterprise (Cloud-hosted) | Custom / annually | |
| Personal (Privately-hosted) | $0 / monthly | |
| Advanced Enterprise (Privately-hosted) | Custom / annually |
Pricing, limits, taxes, model access, and regional availability can change. Verify the purchase-critical details on the official pricing page linked under Sources.
Transparent ranking
Why Weights & Biases scores 76.5
Each factor is scored on a 100-point scale, then combined using the public ToolsRank weights. Engagement and momentum stay at a neutral baseline until measured signals exist, so no tool can gain or lose position from numbers nobody recorded.
Compatibility
Languages, platforms, and integrations
Languages
- English
- Japanese
- Korean
- German
Platforms
- Web
- iOS
- Linux
- macOS
- Windows
Integrations & surfaces
- PyTorch
- Hugging Face
- PyTorch Lightning
- TensorFlow
- Keras
- Scikit-learn
- XGBoost
- LangChain
- LlamaIndex
- CoreWeave
- AWS
- Docker
Community
Reviews and questions
No approved member reviews yet. Editorial factors above are the only rating on this page.
Reviews and questions come from Google-signed members and are checked by an editor before they appear.
Frequently asked
Weights & Biases FAQ
What is the difference between W&B Models and W&B Weave?+
W&B Models is designed for training and fine-tuning machine learning models, offering experiment tracking, hyperparameter sweeps, tables, and model artifact registries. W&B Weave is tailored for generative AI applications, providing tracing, evaluations, prompt playgrounds, and monitoring for LLM pipelines and autonomous agents.
Can I run Weights & Biases on my own infrastructure?+
Yes. Weights & Biases supports self-hosting via Docker and Python on Linux, macOS, or Windows machines. A free Personal license is offered for non-commercial projects, while companies can use self-hosted options under Enterprise plans.
Who qualifies for the W&B Pro plan?+
The Pro plan is designed for early-stage teams and organizations with fewer than 50 employees. Organizations that exceed 50 employees or higher usage thresholds are required to transition to W&B Enterprise.
Is Weights & Biases free for academic researchers?+
Yes. Weights & Biases provides a free academic license for non-profit academic research by students, professors, and postdoctoral researchers with valid institutional email addresses. It includes Pro features, up to 100 seats, 200GB cloud storage, and up to 25GB/mo of Weave data ingestion.
What certifications and security compliance does the platform hold?+
Weights & Biases is certified under ISO/IEC 27001:2022, ISO/IEC 27017:2015, and ISO/IEC 27018:2019, and is compliant with SOC 2 Type II and HIPAA standards. It also supports customer compliance with NIST 800-53 and aligns with GDPR requirements.