# Opik (Comet)

Open-source LLM tracing, evaluation and prompt-optimization platform (Apache-2.0). Opik (Comet) is freemium — a usable free tier with paid plans above it, at comet.com.

## Facts

- **Pricing tier:** Free tier + paid
- **Works on:** Web, Self-hosted, API
- **Works in browser:** Yes

## Capabilities

- Open-source LLM tracing, evaluation and prompt-optimization platform (Apache-2.0)
- Free cloud plan with 25k spans a month, up to 10 team members and 60-day retention
- Self-host with no limits

## FAQ

### What is Opik (Comet)?

Opik (Comet) is listed under LLM Eval & Observability, in the AI Models & Local Execution category on Flocci AI Tools. Open-source LLM tracing, evaluation and prompt-optimization platform (Apache-2.0). It is freemium — a usable free tier with paid plans above it, and it lives at comet.com.

### Is Opik (Comet) free?

Opik (Comet) is freemium: there is a free tier you can work in and paid plans above it. It is one of 429 freemium tools in the catalog, all labelled the same way so you are never surprised by a paywall.

### Can I use Opik (Comet) in a browser, or is there an app?

Opik (Comet) works in a normal browser tab with no install. It is available on the web, self-hosting and an API.

### What can Opik (Comet) do?

Opik (Comet) does 3 things the catalog singles out: Open-source llm tracing, evaluation and prompt-optimization platform (apache-2.0); free cloud plan with 25k spans a month, up to 10 team members and 60-day retention; self-host with no limits.

### What is the best free alternative to Opik (Comet)?

Arize Phoenix is the closest free alternative: it sits in the same LLM Eval & Observability sub-category and is free. Google Stax, Laminar and DeepEval also start free. The full list is on the alternatives page.

## Related

- [Opik (Comet) alternatives](https://aitools.flocci.in/alternatives/opik-comet)
- [LLM Eval & Observability](https://aitools.flocci.in/category/ai-models-local-execution/llm-eval-observability)
- [Best free LLM evaluation and observability tools](https://aitools.flocci.in/best/best-llm-eval-observability)
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Source: Flocci AI Tools — https://aitools.flocci.in/tool/opik-comet

Facts last verified: October 2026