Weight & Biases

Weight & Biases

MLOps platform for experiment tracking

Overview

Weights & Biases offers a developer-first MLOps platform that helps manage the entire ML workflow from development to production. Its tools include Experiments for tracking runs, Sweeps for hyperparameter tuning, and Artifacts for versioning datasets and models, along with data visualizations to compare results. The platform integrates with TensorFlow, PyTorch, and Keras and supports collaboration for individuals and teams, enabling model lineage and reproducibility across projects. The goal is to make ML development more organized and scalable by providing an end-to-end system that emphasizes reproducibility, collaboration, and clear workflow management.

About Weight & Biases

Simplify's Rating
Why Weight & Biases is rated
B-
Rated B on Competitive Edge
Rated B on Growth Potential
Rated C on Differentiation

Industries

Data & Analytics

Enterprise Software

AI & Machine Learning

Company Size

201-500

Company Stage

Acquired

Total Funding

$2B

Headquarters

San Francisco, California

Founded

2017

Simplify Jobs

Simplify's Take

What believers are saying

  • W&B Inference serves LoRA models on CoreWeave GPU clusters.
  • LLM Evaluation Jobs reduce wasted GPU hours during training.
  • Cranium integration adds embedded security and compliance workflows for enterprises.

What critics are saying

  • CoreWeave bundling pushes neutral customers toward competing multi-cloud MLOps tools.
  • CoreWeave pricing pressure drives packaging changes and platform lock-in within 18 months.
  • LangSmith, Databricks, and OpenAI-native tools already match W&B’s expanding feature set.

What makes Weight & Biases unique

  • Founded in 2017 by Lukas Biewald, Chris Van Pelt, and Shawn Lewis.
  • System of record for training, fine-tuning, evaluation, and monitoring.
  • Now paired with CoreWeave’s AI cloud and managed GPU infrastructure.

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Funding

Total Funding

$1.9B

Above

Industry Average

Funded Over

6 Rounds

Acquisition funding comparison data is currently unavailable. We're working to provide this information soon!
Acquisition Funding Comparison
Coming Soon

Benefits

🏝️ Unlimited vacation time

🩺 100% Medical, Dental, and Vision for employees and Family Coverage

🏠 Remote first culture with in-office flexibility in San Francisco

💵 $1000 home office budget with new high-powered laptop

🥇 Truly competitive salary and equity

🚼 12 weeks of Parental leave

📈 401(k)

Growth & Insights and Company News

Headcount

6 month growth

-1%

1 year growth

-1%

2 year growth

-3%
Weights & Biases
Nov 1st, 2025
Product newsletter: Updates and new features for November 2025

From LLM Evaluation Jobs in W&B Models to its new terminal UI, here's what Biases, Inc. shipped in November: Welcome to the November 2025 edition of the Weights & Biases newsletter. Last month, Biases, Inc. launched a brand new terminal UI for Weights & Biases, brought support for LoRA fine-tuned models to W&B Inference, announced LLM evaluation jobs for W&B Models and more. Table of contents. Introducing W&B LEET: A new terminal UI for Weights & Biases. Biases, Inc. is thrilled to roll out its W&B Lightweight Experiment Exploration Tool (LEET), a fast terminal interface to watch your ML training runs, including stats, metrics, and system health. It reads and visualizes live Weights & Biases log files to provide a fast, customizable, browser-free experience in real time. LEET presents an interactive, three-pane dashboard that updates live as your run progresses: * Run overview (left): configuration, environment, and summary metadata * Metrics grid (center): live charts for tracked metrics * System metrics (right): CPU, GPU, and memory consumption W&B LEET is open source and available to users on W&B SDK version 0.23.0 or later. You can access W&B LEET directly from the terminal where your W&B run is active: For a full list of LEET shortcuts and hotkeys, hit h or? to toggle the help screen. You can give it a try here. Bring your LoRA to serve fine-tuned models on W&B Inference. W&B Inference now lets you serve custom fine-tuned models on fully managed CoreWeave GPU clusters without managing infrastructure. Use its OpenAI-compatible Chat Completions API, reference your LoRA artifact in W&B Models along with the base model name, and Biases, Inc.'ll dynamically load your adapter onto a preloaded base model at request time and return the response. It takes just a few lines of code on your local machine to deploy your LoRA adapter on W&B Inference. Checkout this sample notebook to get started or this launch blog post for more information. * Version-controlled serving: The artifact URI explicitly includes the project, run, and version, providing traceability back to the training and hyperparameters used to create the LoRA weights. * Zero infra to manage: You avoid the complexity of setting up and scaling serving infrastructure for every LoRA iteration. The system handles dynamic loading and hot-swapping of your weights in the background. * Faster iteration: Because only the small LoRA weights are updated and managed via artifacts, you can cycle from training to production validation instantly. Saved prompts in W&B Weave Playground. You can now edit, save, and version prompts directly within the W&B Weave Playground. The Playground is great for interactively comparing production traces across different LLMs. Now you can track changes as you refine prompts and pull them into your code using: To try it out, head to https://wandb.ai/inference, pick a model, and click "Try in Playground." This feature is available in its SaaS cloud deployments but will be rolled out to Dedicated shortly. Introducing LLM Evaluation Jobs in W&B Models. You can now evaluate model checkpoints during training on popular public benchmarks without building numerous evaluation harnesses or managing infrastructure with LLM Evaluation Jobs. This gives you early reads on your model's downstream performance so you can course-correct or end unpromising runs. You save GPU hours and wall-clock time. When training or fine-tuning models, you often want an early read on benchmark performance while still in the loop. If results trend poorly, you can adjust hyperparameters or stop the run to avoid waste. Doing this on your own means finding compute, building the evaluation harness, and wiring it into your training pipeline. That work adds little differentiation and slows you down. That changes with LLM Evaluation Jobs in W&B Models. Point to your model checkpoint artifacts or hosted API endpoints, then pick a benchmark. Biases, Inc. provide prebuilt evaluation harnesses for popular public benchmarks using Inspect Evals. Biases, Inc. provision and manage the GPU infrastructure, so there is nothing for you to set up or maintain. Biases, Inc. run the evaluation, store results in your Weights & Biases project, and generate a leaderboard, so you can easily compare your models in your W&B Models workspace. LLM Evaluation Jobs is currently available in public preview for multi-tenant cloud customers. You can check out the docs to learn more. Updated run menu shortcuts in W&B Models. Biases, Inc. has added some new options to the run menu to make your life a little easier: * Actions to copy the run name or the run path to your clipboard * A link right to the Logs tab for a run * Clarification on updating the display name for a run in this workspace vs. the name of the run for the whole project. These also all appear in the menu in the single run views and are available on both its Dedicated and SaaS deployments. Biases, Inc. hope this shaves off a few more seconds for these common actions. That's it for November. If you missed any of its recent product newsletter, you can catch up here: October: Release of Serverless RL. Access and usability improvements to W&B Registry. W&B Weave adds the ability to generate images in Playground and new filter evaluations. W&B Models adds copious quality-of-life improvements to UI and common work streams. September: W&B Inference support for Z.AI's GLM 4-5. W&B Weave introduced no-code evaluations. W&B Models enhanced support for post-training AI agents with reinforcement learning, featuring a sleek traces panel right in the workspace. August: W&B Inference support for DeepSeek V3.1. W&B Weave introduced a new Content API for logging any media type, along with updates like UI-based prompt management, a trace graph view, better markdown rendering, and new latency metrics. W&B Models added practical improvements such as pinned workspace columns and a full-screen media viewer for easier comparison. July: Tool calling support and new models in W&B Inference including GPT OSS, Qwen 3, and Kimi K2. For W&B Weave, Biases, Inc. announced advanced filtering for traces, live dashboards for monitoring trace plots, and the ability to group threads into traces. For W&B Models, Biases, Inc. announced usability improvements for media and updates to full fidelity plots. June: Biases, Inc. announced a new product, W& Inference as well as updates to existing products. For Weave, Biases, Inc. launched online evaluations, pivot tables, new data types. For Models, Biases, Inc. launched CoreWeave Observability and Object Storage integration, and integrated logging with W&B Tables. May: For Weave, Biases, Inc. launched features to trace streaming responses, video support, saved views, and filter by status. For Models, Biases, Inc. launched workspace templates for line plot settings, enhanced color controls, and control media panels in bulk. April: For Weave, Biases, Inc. launched new trace views, the EvaluationLogger API, OpenTelemetry support, custom model support in Weave Playground, and more. For Models, Biases, Inc. announced run metrics notifications, protected aliases in W&B Registry, custom display names, complete console logs for distributed runs and easier ways to view media panels. March: For Weave, Biases, Inc. launched the MCP server and integrations with OpenAI Agents SDK and CrewAI. For Models, Biases, Inc. launched interactive sliders, segment masks, and options to format custom metrics. February: For Weave, Guardrails generally available, great data privacy, and new ways to work with datasets. For Models, new workspaces usability updates, faster and easier share of AI artifacts through Registry, cool line plot updates, and new Reports customization options. January: For Weave, state-of-the-art agent released, run trials in the Weave playground, human annotation scorers, and datasets made easy. For Models, new panel management and improved workspace user experience with unified settings, live preview and a new UX.

VentureBeat
Jun 16th, 2025
Minimax-M1 Is A New Open Source Model With 1 Million Token Context And New, Hyper Efficient Reinforcement Learning

Join the event trusted by enterprise leaders for nearly two decades. VB Transform brings together the people building real enterprise AI strategy. Learn more. Chinese AI startup MiniMax, perhaps best known in the West for its hit realistic AI video model Hailuo, has released its latest large language model, MiniMax-M1 — and in great news for enterprises and developers, it’s completely open source under an Apache 2.0 license, meaning businesses can take it and use it for commercial applications and modify it to their liking without restriction or payment. M1 is an open-weight offering that sets new standards in long-context reasoning, agentic tool use, and efficient compute performance. It’s available today on the AI code sharing community Hugging Face and Microsoft’s rival code sharing community GitHub, the first release of what the company dubbed as “MiniMaxWeek” from its social account on X — with further product announcements expected. MiniMax-M1 distinguishes itself with a context window of 1 million input tokens and up to 80,000 tokens in output, positioning it as one of the most expansive models available for long-context reasoning tasks.The “context window” in large language models (LLMs) refers to the maximum number of tokens the model can process at one time — including both input and output

VentureBeat
Jun 12th, 2025
Cloud Collapse: Replit And Llamaindex Knocked Offline By Google Cloud Identity Outage

Join the event trusted by enterprise leaders for nearly two decades. VB Transform brings together the people building real enterprise AI strategy. Learn moreDays after OpenAI and Google Cloud announced a partnership to support the growing use of generative AI platforms, much of the AI-powered web and tools went down due to an outage of the leading cloud providers.Google Cloud Service Platform (GCP) and some Cloudflare services began experiencing issues around 10:00 a.m. PT today, affecting several AI development tools and data storage services, including ChatGPT and Claude, as well as a variety of other AI platforms.We are aware of a service disruption to some Google Cloud services and we are working hard to get you back up and running ASAP.Please view our status dashboard for the latest updates: https://t.co/sT6UxoRK4R — Google Cloud (@googlecloud) June 12, 2025A GCP spokesperson confirmed the outage to VentureBeat, urging users to check its public status dashboard.GCP said affected services include API Gateway, Agent Assist, Cloud Data Fusion, Contact Center AI Platform, Google App Engine, Google BigQuery, Google Cloud Storage, Identity Platform, Speech-to-Text, Text-to-Speech and Vertex AI Search, among other tools. Google’s mobile development platform, Firebase, also went down.VentureBeat staffers had trouble accessing Google Meet, but other Google services on Workspace remained online.A Cloudflare spokesperson told VentureBeat only “a limited number of services at Cloudflare use Google Cloud and were impacted. We expect them to come back shortly

AiThority
May 5th, 2025
CoreWeave Acquires Weights & Biases

CoreWeave has completed its acquisition of Weights & Biases, enhancing its AI Cloud Platform capabilities. This strategic move aims to accelerate AI innovation and expand growth opportunities following CoreWeave's recent IPO. CEO Michael Intrator praised Weights & Biases for their innovation and engineering excellence, which align with CoreWeave's priorities. Together, they plan to deliver a leading AI Cloud Platform to develop, deploy, and iterate AI more efficiently.

MarketScreener
May 5th, 2025
CoreWeave Acquires Weights & Biases

CoreWeave, Inc. (Nasdaq: CRWV) has completed its acquisition of Weights & Biases, enhancing its AI Cloud Platform capabilities. This strategic move aims to accelerate AI innovation by combining CoreWeave's infrastructure with Weights & Biases' developer platform. The acquisition supports interoperability and aims to empower AI developers. Financial advisors included Evercore and Morgan Stanley for CoreWeave, and Qatalyst Partners for Weights & Biases.

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