W&

Weights & Biases

Infrastructure

MLOps and AI observability platform whose experiment-tracking and Weave tooling help teams monitor and evaluate models in development and production. Acquired by CoreWeave, 2025-05-05; continues to ship under its own name.

Acquired by CoreWeave (2025)

Total funding—

Valuation—

Employees—

Founded2017

HeadquartersSan Francisco, USA

StatusAcquired

Products

Selected offerings — the AI products recorded here, not the vendor's full catalogue.

• W&B Models Platform Sold on its own

  Experiment tracking for model training runs, recording hyperparameters, metrics and artifacts so runs can be compared, swept and reproduced.

• W&B Weave Developer tool Sold on its own

  Tracing, evaluation and production monitoring for LLM and agent applications, capturing each call so prompts and outputs can be scored over time.

Inside Weights & Biases

• W&B Registry Platform Included with the parent

  Curated central repository providing versioning, aliases, lineage tracking and governance for models and datasets across the ML lifecycle.

• W&B Serverless Inference API service

  Hosted inference service for open-source and commercial LLMs (OpenAI, Qwen, Llama, Kimi, Phi, DeepSeek, Z.AI) without managing infrastructure.

• W&B Serverless RL Platform

  Managed reinforcement-learning fine-tuning service for LLMs on CoreWeave's managed GPU cluster, billed per-token for rollouts with automatic scale-to-zero.

• W&B Serverless SFT Platform

  Serverless supervised fine-tuning for LLMs on CoreWeave's managed GPU cluster, run alongside Serverless RL in a unified workflow via the Agent Reinforcement Trainer (ART) API.

Similar products 83

No sourced competitor yet: no filing, vendor document or measured-market report read so far names a rival for this company, so none is asserted. The companies below are the closest by what their products do.

How this list is ranked ↗

NGNebius GroupPublic · $61.6BW&B Models and Managed Service for MLflow do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.5 of 5 capabilitiesShared product typeCompareCCrusoePrivate · $10BW&B Serverless Inference and Crusoe Managed Inference do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.5 of 5 capabilitiesShared product typeCompareCMComet MLPrivate · $70M raisedW&B Weave and Opik both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareBBasetenPrivate · $13BW&B Models and Baseten Training do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareTTuringPrivate · $2.2BW&B Models and RL environments do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; ships agent platform and data service rather than the same layer.2 of 5 capabilitiesDifferent layerCompareTATogether AIPrivate · $8.3BW&B Serverless Inference and Together Dedicated Container Inference do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareLLambdaPrivate · $1.5B raisedW&B Serverless RL and Lambda 1-Click Clusters do comparable work on GPU cloud and model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; ships infrastructure service and model API rather than the same layer.4 of 5 capabilitiesDifferent layerCompareFAFireworks AIPrivate · $17.5BW&B Serverless Inference and Fireworks Inference do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareCCCactus ComputePrivateW&B Models and Cactus Platform do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Cactus Compute's scale not recorded.2 of 5 capabilitiesShared product typeCompareRRunPodPrivateW&B Serverless Inference and Runpod Hub do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; RunPod's scale not recorded.4 of 5 capabilitiesShared product typeCompareMModalPrivate · $466M raisedW&B Serverless Inference and Modal Inference do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareHHeliconeAcquiredW&B Weave and Helicone both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; both acquired, so no independent scale on either side.2 of 5 capabilitiesShared product typeCompareTTolokaPrivateW&B Models and Toloka Arena do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Toloka's scale not recorded.2 of 5 capabilitiesShared product typeCompareKEKakao EnterprisePrivateW&B Models and Kubeflow do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Kakao Enterprise's scale not recorded.5 of 5 capabilitiesShared product typeCompareLLabelboxPrivate · $189M raisedW&B Models and Terra do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareEElasticPublic · $10.2BW&B Weave and Elastic LLM Observability both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareDDatabricksPrivate · $190BW&B Weave and Agent Bricks both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareRReplicatePrivateW&B Serverless Inference and Replicate do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; Replicate's scale not recorded; ships infrastructure service rather than the same layer.2 of 5 capabilitiesDifferent layerCompareNCNAVER CloudPrivateW&B Serverless RL and ML expert Platform do comparable work on GPU cloud and model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; NAVER Cloud's scale not recorded.4 of 5 capabilitiesShared product typeCompareHFHugging FacePrivate · $4.5BW&B Serverless Inference and Hugging Face Hub do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareOOllamaPrivate · $88M raisedW&B Serverless Inference and Ollama Cloud do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; ships infrastructure service and model API rather than the same layer.2 of 5 capabilitiesDifferent layerCompareMModularAcquired ($3.1B deal)W&B Serverless Inference and Modular Cloud do comparable work on model hosting; both also serve buyers who need to serve a model in production; both acquired, so no independent scale on either side.2 of 5 capabilitiesShared product typeCompareNNeo4jPrivate · $2BW&B Models and Neo4j Graph Data Science do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareAAppenPublicW&B Models and AI Data Platform do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Appen's scale not recorded.1 of 5 capabilitiesShared product typeCompareVVMwareAcquiredW&B Serverless Inference and VMware Cloud Foundation Private AI Services do comparable work on model hosting; both also serve buyers who need to serve a model in production; both acquired, so no independent scale on either side; ships infrastructure service rather than the same layer.3 of 5 capabilitiesDifferent layerCompareHCHuawei CloudPrivateW&B Serverless Inference and MaaS do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; Huawei Cloud's scale not recorded.4 of 5 capabilitiesShared product typeCompareSSplunkAcquiredW&B Weave and Splunk Observability Cloud both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; both acquired, so no independent scale on either side.2 of 5 capabilitiesShared product typeCompareAAArize AIPrivateW&B Weave and Arize Phoenix both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale; Arize AI's scale not recorded.1 of 5 capabilitiesShared product typeCompareCCivitaiPrivate · $5.1M raisedW&B Serverless Inference and Civitai API do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareUUnslothPrivateW&B Models and Unsloth do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Unsloth's scale not recorded.2 of 5 capabilitiesShared product typeCompareDDeepchecksAbsorbedOverlaps on evaluation and observability; Weights & Biases is acquired, with no independent scale; Deepchecks is absorbed, with no independent scale.1 of 5 capabilitiesShared product typeCompareAAArthur AIPrivate · $62.7M raisedW&B Weave and Arthur Engine both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareBBraintrustPrivate · $125M raisedOverlaps on evaluation and observability; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareGGalileoAcquired ($68M deal)Overlaps on evaluation and observability; both acquired, so no independent scale on either side.1 of 5 capabilitiesShared product typeCompareNNVIDIAPublic · $5.1TW&B Models and NVIDIA AI Workbench do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.5 of 5 capabilitiesShared product typeCompareEEleutherAINonprofitW&B Models and GPT-NeoX do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; EleutherAI is a nonprofit, with no independent scale.2 of 5 capabilitiesShared product typeCompareMAMistral AIPrivate · $13.8BW&B Models and Mistral Forge do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareFAFiddler AIPrivate · $100M raisedOverlaps on evaluation and observability; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareFFalPrivateW&B Serverless Inference and fal Serverless do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; Fal's scale not recorded; ships AI agent, infrastructure service and 1 more rather than the same layer.3 of 5 capabilitiesDifferent layerCompareCSCerebras SystemsPublic · $44.4BW&B Models and Cerebras Training Cloud do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareMMicrosoftPublic · $3.7TW&B Weave and Observability in Foundry Control Plane both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareLLangfuseAcquiredW&B Weave and Langfuse both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; both acquired, so no independent scale on either side.1 of 5 capabilitiesShared product typeCompareIMInsilico MedicinePublic · $4.3BW&B Models and MMAI Gym do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompare44ParadigmPublic · $2BW&B Models and 4Paradigm Sage HyperCycle do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareHHumainPrivateW&B Serverless RL and HUMAIN COMPUTE do comparable work on GPU cloud and model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Humain's scale not recorded.3 of 5 capabilitiesShared product typeCompareLALiquid AIPrivateW&B Models and LEAP do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Liquid AI's scale not recorded.2 of 5 capabilitiesShared product typeCompareAAlibabaPublic · $273.4BW&B Models and Alibaba Cloud Platform for AI (PAI) do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareSASnorkel AIPrivate · $1.3BW&B Models and Snorkel Flow do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareTMThinking Machines LabPrivate · $12BW&B Models and Tinker do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareAAMDPublic · $785.1BW&B Serverless Inference and AMD Enterprise AI Reference Stack do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareDDataikuPrivate · $3.7BW&B Models and Dataiku do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareIIBMPublic · $216.6BW&B Models and IBM watsonx.ai do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareCClickHousePrivate · $1.1B raisedW&B Weave and ClickStack both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareSSiemensPublic · $244.7BW&B Models and Rapidminer AI Studio do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareALAI21 LabsPrivate · $1.4BW&B Models and AI21 Post-Training do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareAMApplied MaterialsPublic · $380.7BW&B Models and SmartFactory AI IQworks do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareIIntelPublic · $463.7BW&B Models and Intel Geti do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareHHuaweiPrivateW&B Serverless Inference and MindIE do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; Huawei's scale not recorded.4 of 5 capabilitiesShared product typeCompareVVercelPrivate · $9.3BW&B Serverless Inference and Vercel AI Gateway do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareTTencentPublic · $510.1BW&B Models and Tencent Cloud TI Platform do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareLSLM StudioPrivateW&B Serverless Inference and LM Studio do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; LM Studio's scale not recorded; ships AI agent and application rather than the same layer.2 of 5 capabilitiesDifferent layerCompareKKuaishouPublic · $18.6BW&B Models and Vanchin do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareBBaiduPublic · $31.6BW&B Serverless RL and Baidu Baige AI Computing Platform do comparable work on GPU cloud and model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareYYandexPublicW&B Models and Yandex DataSphere do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Yandex's scale not recorded.3 of 5 capabilitiesShared product typeCompareLLangChainPrivate · $160M raisedW&B Weave and LangSmith both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareAAlphabet (Google)Public · $4.2TW&B Models and Gemini Enterprise Agent Platform (formerly Vertex AI) do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareCCoherePrivate · $7BW&B Serverless Inference and Model Vault do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareDDatadogPublic · $84.9BW&B Weave and Agent Observability both serve buyers who need to watch an AI agent for suspicious or runaway behaviour; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareMPMeta PlatformsPublic · $1.5TW&B Serverless Inference and Meta Model API do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale; ships AI agent, agent platform and 2 more rather than the same layer.2 of 5 capabilitiesDifferent layerCompareHAHume AIPrivateW&B Models and Human Feedback API both serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Hume AI's scale not recorded.1 of 5 capabilitiesShared product typeCompareOOraclePublic · $454.4BW&B Models and OCI Vision do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareAAmazonPublic · $2.8TW&B Models and Amazon SageMaker AI do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareDTDell TechnologiesPublic · $360.7BW&B Serverless Inference and Dell Enterprise Hub do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareEEncordPrivateW&B Models and Encord both serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; Encord's scale not recorded.1 of 5 capabilitiesShared product typeCompareAAdobePublic · $115.9BW&B Models and Adobe Firefly Custom Models do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareSSenseTimePublic · $7.7BW&B Serverless RL and SenseCore do comparable work on GPU cloud and model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompareDDecartPrivate · $4BW&B Serverless Inference and Cogito do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.3 of 5 capabilitiesShared product typeCompareGGitLabPublic · $8.3BW&B Serverless Inference and GitLab Duo Agent Platform Self-Hosted do comparable work on model hosting; both also serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.2 of 5 capabilitiesShared product typeCompareSSpace42Public · $2.6BW&B Models and GIQ do comparable work on model training; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareBFBlack Forest LabsPrivate · $3.3BW&B Serverless RL and Open Weights Licensing do comparable work on model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale; ships application, infrastructure service and 1 more rather than the same layer.1 of 5 capabilitiesDifferent layerCompareUUniphorePrivate · $2.5BW&B Serverless Inference and Uniphore Model Layer both serve buyers who need to serve a model in production; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareLLovablePrivate · $13.3BW&B Serverless Inference and Lovable Cloud do comparable work on model hosting; Weights & Biases is acquired, with no independent scale.1 of 5 capabilitiesShared product typeCompareCCoreWeavePublic · $48.5BW&B Serverless RL and CoreWeave AI Cloud do comparable work on GPU cloud and model training; both also serve buyers who need to train or fine-tune a model; Weights & Biases is acquired, with no independent scale.4 of 5 capabilitiesShared product typeCompare

Closest alternatives are pairs a vendor page itself compares. Similar products are matched from what each product does; nothing in that group is asserted as a rivalry.

Sources

Founded

Company disclosure · 31 Aug 2026

Weights & Biases' own About page: "When Weights & Biases was founded by Lukas Biewald, Chris Van Pelt, and Shawn Lewis in 2017..."

Status

Press release · 5 May 2025

CoreWeave's own investor-relations release confirming the completed acquisition, 2025-05-05. CoreWeave is already in this directory, so this is a parent/subsidiary pair. Weights & Biases continues to operate and ship product under its own name, so the record is kept rather than folded into CoreWeave's page -- same treatment as Darktrace/Thoma Bravo.

Open Weights & Biases in the directory

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