Honest pros, cons, and verdict on this llm observability & evals tool
✅ Open-source positioning with an Apache-2 tag gives teams a clearer inspection and extensibility path than fully closed LLM observability products.
Starting Price
Free
Free Tier
Yes
Category
LLM Observability & Evals
Skill Level
Developer
Open-source LLM evaluation and observability framework: trace, evaluate, monitor, and improve LLM applications.
Opik by Comet is an Apache-2 open-source LLM evaluation and observability framework with a $0 Open Source plan, a $0 Free Cloud plan for up to 10 team members, 25k spans per month, 60-day retention, and a $19 per month Pro Cloud plan for up to 50 team members and 100k spans per month. Based on the supplied product metadata and current Comet pricing information verified on 2026-06-04, its core focus is the operational lifecycle of LLM applications: tracing application behavior, evaluating outputs, monitoring quality over time, and using those signals to improve prompts and model-backed workflows. This places Opik in the LLM observability and evals category rather than in a general-purpose chatbot, model provider, or prompt-only tool category.
The tool is especially relevant for engineering and machine learning teams that need more structure around how LLM applications behave in development and production. LLM systems can fail in ways that are difficult to detect with ordinary logs alone: responses may be factually weak, inconsistent, overly verbose, missing required constraints, or sensitive to small prompt and retrieval changes. Opik’s stated scope addresses that problem by combining tracing and evaluation workflows so teams can inspect what happened in an LLM call path and judge whether the resulting behavior meets expectations.
per month
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Learn more →Opik by Comet delivers on its promises as a llm observability & evals tool. While it has some limitations, the benefits outweigh the drawbacks for most users in its target market.
Open-source LLM evaluation and observability framework: trace, evaluate, monitor, and improve LLM applications.
Yes, Opik by Comet is good for llm observability & evals work. Users particularly appreciate open-source positioning with an apache-2 tag gives teams a clearer inspection and extensibility path than fully closed llm observability products.. However, keep in mind published opik pricing now lists plan names, prices, seat counts, span limits, and retention for open source, free cloud, pro cloud, and enterprise, but buyers should still verify overage rules and contract terms directly before purchase..
Yes, Opik by Comet offers a free tier. However, premium features unlock additional functionality for professional users.
Opik by Comet is best for Tracing LLM application requests to understand how prompts, model calls, and application steps contribute to final outputs. and Building repeatable evaluation workflows for LLM features before shipping changes to production.. It's particularly useful for llm observability & evals professionals who need advanced features.
Popular Opik by Comet alternatives include LangSmith, Arize AI, Helicone. Each has different strengths, so compare features and pricing to find the best fit.
Last verified March 2026