Machine Learning · head to head
Comet ML vs Weights & Biases
Comet ML
Machine Learning
Platform for tracking, comparing, and optimizing ML experiments
- From
- Free
- Rated
- -
Weights & Biases
Machine Learning
Developer tools for machine learning
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Comet ML the free cloud tier caps data at 25,000 spans a month with 60 day retention; Weights & Biases pricing can be prohibitive for large teams without enterprise discounts
- They diverge on capability: Comet ML covers Code versioning, Weights & Biases covers Dataset versioning.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Comet ML and Weights & Biases actually diverge.
| Attribute | Comet ML | Weights & Biases |
|---|---|---|
| Pricing model | freemium | Unknown |
| Platforms | Web, Linux, Mac, Windows | Web, Python SDK, REST API |
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Machine Learning), founded (2017).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Comet ML
- Code versioning
- Hyperparameter optimization
- Production monitoring
- scikit-learn
Only in Weights & Biases
- Dataset versioning
- Hyperparameter sweeps
- Collaborative dashboards
- Lightning
Both cover
- Experiment tracking
- Model registry
- PyTorch
- TensorFlow
- Keras
- Hugging Face
- Web support
- Linux support
- Mac support
- Windows support
What people use each for
The jobs each tool is most often brought in to do.
Comet ML
- LLM observability and monitoringnot Weights & Biases
- AI agent testing and debuggingnot Weights & Biases
- Experiment tracking for machine learningnot Weights & Biases
- Model registry and version managementnot Weights & Biases
- ML model training monitoringnot Weights & Biases
Weights & Biases
- Machine learningnot Comet ML
- Data analysisnot Comet ML
- Model trainingnot Comet ML
- Predictive analyticsnot Comet ML
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Comet ML
- The free cloud tier caps data at 25,000 spans a month with 60 day retention
- Retention stays at 60 days even on the paid Pro plan, and extending it is a $29 per 100k spans add on
- Overage on Pro is $5 per additional 100,000 spans
- The free MLOps tier is a single user with 100 GB of storage and training hours governed by a fair usage policy
- Pro MLOps is $19 per user per month and caps the team at 10 users
Weights & Biases
- Pricing can be prohibitive for large teams without enterprise discounts
- Limited integrations compared to some competitors
- Dashboard customization options limited on lower plans
- Requires some setup and configuration knowledge
Pricing, plan by plan
Comet ML
Free- Free CloudFree
- Up to 10 team members
- 25,000 spans per month
- 60-day data retention
- Pro Cloud$19/month
- Up to 50 team members
- 100,000 spans per month
- 60-day data retention
- MLOps FreeFree
- 1 user with fair usage policy
- Experiment tracking
- Dataset management
- MLOps Pro$19/user/month
- Up to 10 users
- 1,500 training hours included
- 500GB storage included
Weights & Biases
Free- FreeFree
- 5 model seats
- 5 GB storage
- 1 GB/month Weave ingestion
- Pro$60/month
- 10 seats
- 100 GB storage
- Private projects
- Teams$179/month
- Team collaboration
- Advanced analytics
- Dedicated support
Which should you pick?
Choose Comet ML if
- You need code versioning.
- You want to start without paying.
- You work on Web, Linux, Mac, Windows.
- You also want hyperparameter optimization.
Choose Weights & Biases if
- You need dataset versioning.
- You want to start without paying.
- You work on Web, Python SDK, REST API.
- You also want hyperparameter sweeps.
Questions people ask
- Is Comet ML or Weights & Biases better?
- Neither clearly leads. Comet ML starts at Free and Weights & Biases at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Comet ML or Weights & Biases?
- Comet ML starts at Free and Weights & Biases at Free.
- Does Comet ML or Weights & Biases run on more platforms?
- Comet ML runs on Web, Linux, Mac, Windows. Weights & Biases runs on Web, Python SDK, REST API.
- Can I use Comet ML for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Comet ML best used for?
- Comet ML is most often used for llm observability and monitoring, ai agent testing and debugging, experiment tracking for machine learning, model registry and version management. Of those, llm observability and monitoring and ai agent testing and debugging are not what Weights & Biases is typically brought in for.
- What can Comet ML do that Weights & Biases cannot?
- Comet ML covers Code versioning, Hyperparameter optimization, Production monitoring, scikit-learn. Weights & Biases covers Dataset versioning, Hyperparameter sweeps, Collaborative dashboards, Lightning. Both handle Experiment tracking, Model registry, PyTorch, TensorFlow.
Answered from the vendors’ own pages
Comet ML: Does Comet.ml offer a free plan?
Yes, Comet.ml offers free tiers for both Opik (cloud observability) and MLOps platforms. Free Cloud Opik includes up to 10 team members and 25,000 spans/month. Free MLOps tier is limited to 1 user.
SourceWeights & Biases: Does Weights & Biases have a free plan?
Yes. The Free tier includes 5 model seats, 5 GB storage, and 1 GB/month Weave ingestion. Academic users get unlimited tracked hours, 200 GB storage, and 100 seats at no cost.
SourceComet ML: How many team members can use the free Comet.ml tier?
Free Cloud supports up to 10 team members. The Pro Cloud plan supports up to 50 team members at $19/month.
SourceWeights & Biases: What are the paid plans for Weights & Biases?
Pro starts at $60/month with 10 seats and 100 GB storage. Team plans start at $179/month. Enterprise pricing is custom.
SourceComet ML: What is a span in Comet.ml pricing?
A span represents a single tracked operation such as model requests or function calls. Free Cloud tier includes 25,000 spans per month.
SourceWeights & Biases: What machine learning features does W&B provide?
Weights & Biases captures hyperparameters, metrics, and model outputs automatically. Features include experiment tracking, interactive Reports for sharing findings, Artifacts for managing datasets and models, advanced hyperparameter sweeps, and model deployment tools.
SourceComet ML: Does Comet.ml offer academic pricing?
Yes, a free Pro plan is available for academic users; verification is required via signup.
SourceRelated pages
More on Weights & Biases
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