Comet Opik

Trace, evaluate and test LLM applications throughout development.

evalstracing
Websitecomet.com
CategoryAI & machine learning
PricingFreemium
Card requiredNo
Open sourceYes
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ABOUT

What is Comet Opik?

Comet Opik is an open-source LLM observability and evaluation platform. It captures traces from your LLM calls , inputs, outputs, token counts, latency and costs and lets you attach evaluation scores to each trace. The self-hosted edition is fully featured and has no trace limits, which makes it the go-to option for teams that cannot send production data to a third-party cloud.

BEFORE YOU SIGN UP

What you should know

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Unlimited self-hosted editionDeploy via Docker Compose and have no limits on traces, datasets or experiments. Full feature parity with the cloud product.
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Built-in LLM-as-a-judgeDefine evaluation criteria in natural language and have Opik automatically score traces using a model of your choice as the judge.
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Self-hosting requires DockerThe self-hosted edition runs via Docker Compose. It is straightforward to set up but adds infrastructure responsibility compared to a fully managed cloud product.
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Cloud Free has fixed span and retention limitsThe hosted Free plan supports up to 10 members, 25,000 spans per month and 60 days of retention. Higher-volume workloads need Pro or self-hosting.

COMMUNITY

From the forums

Opik benefits from Comet's established reputation in the ML experiment tracking space. Developers on r/MachineLearning praise the self-hosting story as a key differentiator over Braintrust. The cloud free tier's monthly trace limit is the most common complaint. The open-source edition's Docker Compose setup is noted as straightforward, though resource-intensive for teams running on modest infrastructure.

— Community sentiment

💬Discuss on Reddit ↗

SEE ALSO · AI & machine learning

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Guides mentioning Comet Opik

📖Tutorial

How to install Comet Opik on a VPS

Self-host LLM traces, evaluations and prompt observability

2026-07-30·4 min read

ABOUT US

Honest, independent, no fluff.

No paid placements. Just a clear look at what this does, what it costs, and what to know before you commit.

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FAQ

Questions, answered.

Can I migrate data from the cloud to self-hosted?＋

Opik does not currently offer a migration export tool between cloud and self-hosted instances. Plan your deployment model before accumulating significant trace history.

How does Opik compare to Langfuse?＋

Both are open-source LLM observability tools with self-hosted and cloud options. Opik comes from Comet's ML experiment tracking background and has stronger dataset management. Langfuse has a larger community and more third-party integrations at this point.