Machine Learning · head to head
Comet ML vs OpenRouter
Comet ML
Machine Learning
Platform for tracking, comparing, and optimizing ML experiments
- From
- Free
- Rated
- -
OpenRouter
Machine Learning
Unified API gateway routing requests across 500+ models from 80+ providers
- 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; OpenRouter no free tier; all usage incurs cost
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Comet ML and OpenRouter actually diverge.
| Attribute | Comet ML | OpenRouter |
|---|---|---|
| Pricing model | freemium | usage-based |
| Platforms | Web, Linux, Mac, Windows | API, Web |
| Founded | 2017 | Unknown |
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Machine Learning).
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 OpenRouter
Nothing recorded that Comet ML does not also cover.
What people use each for
The jobs each tool is most often brought in to do.
Comet ML
- LLM observability and monitoringnot OpenRouter
- AI agent testing and debuggingnot OpenRouter
- Experiment tracking for machine learningnot OpenRouter
- Model registry and version managementnot OpenRouter
- ML model training monitoringnot OpenRouter
OpenRouter
- Multi-model applications optimising for cost or performancenot Comet ML
- Provider-agnostic deployments avoiding vendor lock-innot Comet ML
- Enterprise applications with custom data policies and provider requirementsnot Comet ML
- Development workflows testing multiple models without code changesnot 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
OpenRouter
- No free tier; all usage incurs cost
- Pricing varies by model; specific rates not published on main site without account access
- Adds latency through additional routing layer compared to direct provider APIs
- Dependent on upstream provider uptime and API compatibility
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$19/user/month
- Up to 10 users
- 1,500 training hours included
- 500GB storage included
OpenRouter
Free- FreeFree
- 50 requests per day
- Access to 25+ free models across 4 providers
- Community support
- Pay-as-you-go$null/variable
- 5.5% platform fee on inference costs
- Access to 500+ models across 80+ providers
- Email support
- Enterprise$null/custom
- Negotiable platform fees
- 200,000 USD of list price inference per month with no fees, then 5% fee after
- SSO/SAML support
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.
Questions people ask
- Is Comet ML or OpenRouter better?
- Neither clearly leads. Comet ML starts at Free and OpenRouter at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Comet ML or OpenRouter?
- Comet ML starts at Free and OpenRouter at Free.
- Does Comet ML or OpenRouter run on more platforms?
- Comet ML runs on Web, Linux, Mac, Windows. OpenRouter runs on API, Web.
- 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 OpenRouter is typically brought in for.
- What can Comet ML do that OpenRouter cannot?
- Comet ML covers Experiment tracking, Code versioning, Model registry, Hyperparameter optimization.
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.
SourceOpenRouter: How much does OpenRouter charge?
OpenRouter charges a 5.5% platform fee on top of the actual inference costs from selected models. Customers purchase credits on a pay-as-you-go basis with no subscriptions or minimum spend requirements.
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.
SourceOpenRouter: Is there a free tier?
Yes. OpenRouter offers a free tier with 50 requests per day and access to 25+ free models across 4 providers. The free tier provides community support only.
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.
SourceOpenRouter: What does the Enterprise plan include?
The Enterprise plan includes 200,000 USD of list price inference per month at no cost, with a 5% platform fee applied to usage above that threshold. It also includes SSO/SAML support, contractual SLAs, and dedicated support with a shared Slack channel.
SourceComet ML: Does Comet.ml offer academic pricing?
Yes, a free Pro plan is available for academic users; verification is required via signup.
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