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Machine Learning · head to head

Comet ML vs Grafana Loki

Comet ML logo

Comet ML

Machine Learning

Platform for tracking, comparing, and optimizing ML experiments

From
Free
Rated
-
Full reviewWebsite
Grafana Loki logo

Grafana Loki

Logging

Log Aggregation for Grafana Stack

From
Free
Rated
-
Full reviewWebsite

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; Grafana Loki grafana Cloud Logs Pro plan includes only 30-day retention; retention beyond 30 days requires Enterprise plan with minimum $25,000 annual commitment
  • They diverge on capability: Comet ML covers Experiment tracking, Grafana Loki covers Log aggregation.

Where they differ

Only the attributes on which Comet ML and Grafana Loki actually diverge.

Attributes where Comet ML and Grafana Loki differ
AttributeComet MLGrafana Loki
PlatformsWeb, Linux, Mac, WindowsSelf-hosted (open source), Managed (Grafana Cloud Logs), Enterprise (self-managed with support)
CategoryMachine LearningLogging
Founded20172014

Identical on both: starting price (Free), pricing model (freemium), 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 Grafana Loki

  • Log aggregation
  • Label-based indexing
  • LogQL language
  • Cost-effective
  • API
  • Webhooks
  • REST
  • Api support

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 Grafana Loki
  • AI agent testing and debuggingnot Grafana Loki
  • Experiment tracking for machine learningnot Grafana Loki
  • Model registry and version managementnot Grafana Loki
  • ML model training monitoringnot Grafana Loki

Grafana Loki

  • Cost-sensitive organisations deploying Kubernetes and Prometheus ecosystemsnot Comet ML
  • Teams needing index-free log aggregation for high-volume environmentsnot 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

Grafana Loki

  • Grafana Cloud Logs Pro plan includes only 30-day retention; retention beyond 30 days requires Enterprise plan with minimum $25,000 annual commitment
  • Open-source version requires self-hosting all infrastructure including storage and scaling

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

Grafana Loki

Free

No published plan breakdown. See the Grafana Loki 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.
Comet ML review

Choose Grafana Loki if

  • You need log aggregation.
  • You want to start without paying.
  • You work on Self-hosted (open source), Managed (Grafana Cloud Logs), Enterprise (self-managed with support).
  • You also want label-based indexing.
Grafana Loki review

Questions people ask

Is Comet ML or Grafana Loki better?
Neither clearly leads. Comet ML starts at Free and Grafana Loki at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Comet ML or Grafana Loki?
Comet ML starts at Free and Grafana Loki at Free.
Does Comet ML or Grafana Loki run on more platforms?
Comet ML runs on Web, Linux, Mac, Windows. Grafana Loki runs on Self-hosted (open source), Managed (Grafana Cloud Logs), Enterprise (self-managed with support).
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 Grafana Loki is typically brought in for.
What can Comet ML do that Grafana Loki cannot?
Comet ML covers Experiment tracking, Code versioning, Model registry, Hyperparameter optimization. Grafana Loki covers Log aggregation, Label-based indexing, LogQL language, Cost-effective. 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.

Source
Grafana Loki: Is there a free tier for Grafana Cloud?

Yes, Grafana Cloud has a Free Forever plan at no cost with no registration required. The free tier is suitable for personal projects and early-stage startups.

Source
Comet 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.

Source
Grafana Loki: How long is data retained in Grafana's free plan?

The free tier retains metrics, logs, traces, and profiles for 14 days.

Source
Comet 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.

Source
Grafana Loki: What is the minimum cost for Grafana Enterprise?

Grafana Enterprise has a minimum annual commitment of 25,000 dollars.

Source
Comet ML: Does Comet.ml offer academic pricing?

Yes, a free Pro plan is available for academic users; verification is required via signup.

Source
Grafana Loki: Do I need a credit card to use Grafana's free tier?

No, Grafana Cloud's Free Forever plan requires no credit card to get started.

Source
Grafana Loki: How is Grafana Cloud billed?

Grafana Cloud Pro starts at 19 dollars per month with usage-based charges on top. Billing is monthly based on your consumption. Grafana offers automatic volume discounts based on your spending.

Source
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