Weights & Biases Weave
W&B Weave is a toolkit for tracing, evaluating, and monitoring GenAI applications and agentic systems, built by Weights & Biases.
Reviewed by Mathijs Bronsdijk · Updated Apr 13, 2026

What is Weights & Biases Weave?
Weights & Biases Weave is a toolkit for building, evaluating, and monitoring generative AI applications and agentic systems, offered as part of the broader Weights & Biases platform. It targets data scientists, ML engineers, researchers, and developers who need visibility into how their AI applications behave, from initial prompt exploration through production monitoring. Where traditional ML tooling focuses on model training, Weave adds a dedicated layer for the GenAI application lifecycle, covering tracing, evaluations, guardrails, and continuous improvement in production. It sits alongside W&B's existing experiment tracking and training infrastructure, giving teams a single platform to manage both model development and application observability.
Key Features
- Traces: Captures and visualizes the execution of AI applications step by step and is easier to explore and debug what happened during a run.
- Evaluations: Provides structured evaluation workflows so teams can rigorously assess AI application quality before and after changes.
- Playground: An interactive environment for exploring different prompts and models without writing code for every test.
- Agents: Observability tools built specifically for agentic systems, where multiple AI components interact in sequences or loops.
- Guardrails: Detects and blocks prompt injection attacks and harmful outputs before they reach end users.
- Monitors: Tracks AI application behavior in production on an ongoing basis, supporting continuous improvement after deployment.
- Experiments: Tracks and visualizes machine learning experiments across runs, helping teams compare results and spot regressions.
- Registry: A shared space to publish and version AI models and datasets so they can be reused across teams.
Use Cases
- Data Scientists tracking ML experiments: Teams use Weave's experiment tracking and visualization tools to compare runs, identify what changed between results, and maintain a clear record of model development progress.
- ML Engineers optimizing model performance: Engineers apply hyperparameter optimization tools to systematically improve model quality without manual trial and error.
- Developers debugging AI applications: Developers use the Traces feature to step through application execution, pinpoint where an AI pipeline produced unexpected output, and shorten the iteration cycle.
- Researchers documenting and sharing findings: Research teams use Reports to capture AI insights in a shareable format, supporting collaboration across groups or with external stakeholders.
Strengths and Weaknesses
Strengths:
- Covers both the model development side (experiments, sweeps, training) and the GenAI application side (traces, evaluations, guardrails) within one platform.
- Dedicated observability tooling for agentic systems, which most general-purpose monitoring tools do not address directly.
- Supports Python and TypeScript, with integrations for GitHub and VS Code, fitting into common developer workflows.
- Available via API so teams to integrate Weave data into their own tooling or automate workflows programmatically.
Weaknesses:
- Pricing is not publicly listed, which makes it difficult to evaluate cost before contacting the vendor.
- Some features, particularly around agentic observability and evaluation pipelines, may require a higher level of technical knowledge to configure and use effectively.
Pricing
Pricing details for Weights & Biases Weave are not publicly listed. Prospective users should contact Weights & Biases directly through the website or reach out to support at [email protected] for pricing information relevant to their team size and use case.
FAQ
What is Weights & Biases Weave?
Weights & Biases Weave is a toolkit for building, evaluating, and monitoring generative AI applications and agentic systems. It is offered as part of the broader Weights & Biases platform and covers the full GenAI application lifecycle, including tracing, evaluations, guardrails, and production monitoring.
What is Weave used for?
Weave is used to track, debug, and monitor AI applications from initial development through production. Its core features include Traces for stepping through application execution, Evaluations for assessing output quality, and Monitors for tracking behavior after deployment.
What does Weights & Biases do?
Weights & Biases provides a platform for managing both model development and AI application observability. It includes tools for experiment tracking, hyperparameter optimization, model and dataset versioning, and, through Weave, dedicated tooling for generative AI applications and agentic systems.
How is Weave different from traditional ML tooling?
Traditional ML tooling focuses on model training, whereas Weave adds a dedicated layer for the GenAI application lifecycle. This includes tracing application execution, running structured evaluations, applying guardrails, and monitoring production behavior on an ongoing basis.
What are Traces in Weave?
Traces capture and visualize the execution of AI applications step by step. Developers use them to pinpoint where a pipeline produced unexpected output and shorten the iteration cycle during debugging.
What are Evaluations in Weave?
Evaluations provide structured workflows for assessing AI application quality before and after changes. Teams use them to rigorously measure output quality at defined points in the development process.
What are Guardrails in Weave?
Guardrails detect and block prompt injection attacks and harmful outputs before they reach end users. They are applied during inference as a protective layer within an AI application.
What is the Playground feature in Weave?
The Playground is an interactive environment for exploring different prompts and models without writing code for every test. It is intended to speed up early-stage prompt and model exploration.
What does the Agents feature in Weave do?
The Agents feature provides observability tools built specifically for agentic systems, where multiple AI components interact in sequences or loops. Most general-purpose monitoring tools do not address agentic systems directly.
What are Monitors in Weave?
Monitors track AI application behavior in production on an ongoing basis. They support continuous improvement after an application has been deployed.
Who is Weave designed for?
Weave targets data scientists, ML engineers, researchers, and developers who need visibility into how their AI applications behave. It is designed to serve teams working across both model development and GenAI application deployment.
What is the Registry in Weave?
The Registry is a shared space to publish and version AI models and datasets so they can be reused across teams. It supports collaboration and consistency when multiple groups are working from common assets.
How does Weave fit into the broader Weights & Biases platform?
Weave sits alongside W&B's existing experiment tracking and training infrastructure, giving teams a single platform to manage both model development and application observability. It does not replace the training-focused tooling but adds a dedicated layer for generative AI applications.