Machine Learning · head to head
Comet ML vs Fathom
Comet ML
Machine Learning
Platform for tracking, comparing, and optimizing ML experiments
- From
- Free
- Free plan
- Yes
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; Fathom team plan requires minimum 2 users; cannot purchase single seat at team pricing
- They diverge on capability: Comet ML covers Experiment tracking, Fathom covers Auto-recording.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Comet ML and Fathom actually diverge.
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).
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
- Experiment tracking
- Code versioning
- Model registry
- Hyperparameter optimization
- Production monitoring
- PyTorch
- TensorFlow
- Keras
Only in Fathom
- Auto-recording
- AI summaries
- Transcription
- Highlight clips
- Zoom
- Google Meet
- HubSpot
- Salesforce
Both cover
- Web support
What people use each for
The jobs each tool is most often brought in to do.
Comet ML
- LLM observability and monitoringnot Fathom
- AI agent testing and debuggingnot Fathom
- Experiment tracking for machine learningnot Fathom
- Model registry and version managementnot Fathom
- ML model training monitoringnot Fathom
Fathom
- AI-powered meeting transcription and automatic note-taking for sales teams and professionalsnot Comet ML
- Meeting analysis with AI scorecards and action item generation that syncs to CRMsnot 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
Fathom
- Team plan requires minimum 2 users; cannot purchase single seat at team pricing
- CRM field sync and deal view summaries available only on Business plan ($34/user/month) and above
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
Fathom
FreeNo published plan breakdown. See the Fathom review.
Which should you pick?
Choose Comet ML if
- You need experiment tracking.
- You want to start without paying.
- You work on Web, Linux, Mac, Windows.
- You also want code versioning.
Choose Fathom if
- You need auto-recording.
- You want to start without paying.
- You work on Web, Zoom, Google Meet, Microsoft Teams.
- You also want ai summaries.
Questions people ask
- Is Comet ML or Fathom better?
- Neither clearly leads. Comet ML starts at Free and Fathom at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Comet ML or Fathom?
- Comet ML starts at Free and Fathom at Free.
- Does Comet ML or Fathom run on more platforms?
- Comet ML runs on Web, Linux, Mac, Windows. Fathom runs on Web, Zoom, Google Meet, Microsoft Teams.
- 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 Fathom is typically brought in for.
- What can Comet ML do that Fathom cannot?
- Comet ML covers Experiment tracking, Code versioning, Model registry, Hyperparameter optimization. Fathom covers Auto-recording, AI summaries, Transcription, Highlight clips. Both handle Web support.
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.
SourceFathom: What is the most affordable paid plan for individuals, and what does it include?
Fathom Premium costs $20 per month (or $16 per month billed annually). It includes advanced summaries, action items, and a conversational AI assistant, in addition to the features in the free plan.
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.
SourceFathom: What is included in Fathom's free plan?
The free plan includes unlimited recordings, transcriptions, AI summaries, clips, and playlists at no cost forever.
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.
SourceFathom: How much does the Team plan cost per user, and what features does it add?
The Team plan costs $19 per month per user (minimum 2 users, or $15 per month annually). It includes everything from Premium plus global search, collaboration features, and team playlists.
SourceComet ML: Does Comet.ml offer academic pricing?
Yes, a free Pro plan is available for academic users; verification is required via signup.
SourceFathom: What trial or guarantee is available before committing to a paid plan?
All paid plans offer a 90-day guarantee to test features risk-free.
SourceFathom: Does Fathom offer free or discounted plans for startups or nonprofits?
Yes, qualified portfolio companies get up to 2 years free, and nonprofits can apply for 10 free seats.
SourceRelated pages
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- Fathom vs DeepSeek
- Fathom vs Grok
- Fathom vs NotebookLM
- Fathom vs RunPod
- Fathom vs Pika
- Fathom vs D-ID
- Fathom vs Anthropic API
- Fathom vs ChatGPT
- Fathom vs Rev
- Fathom vs Aider
- Fathom vs Lambda Labs
- Fathom vs Leonardo AI
- Fathom vs Murf