What is Opik and how does it differ from other LLM observability tools?

Opik is an open-source LLM observability and evaluation platform that connects trace data to actionable code fixes. It offers end-to-end tracing, silent error detection with Diagnostics, an AI assistant (Ollie) that suggests fixes, and automated test suites. Unlike others, it is both truly open source and powered by Comet's enterprise infrastructure for reliability at scale.

Is there a free plan for Opik?

Yes. Opik offers a Free Cloud plan ($0) that includes up to 10 team members, 25k spans per month, 60-day data retention, and features like agent tracing, test suites, and a trial of the Ollie assistant. Additionally, an open-source version is available on GitHub for self-hosting.

What is a 'span' in Opik?

A 'span' represents a single unit of work within a trace, such as an LLM call, a tool invocation, or a retrieval step. Spans measure time, cost, and input/output data. Each trace is composed of multiple spans, and Opik uses them to track performance and errors.

Can I self-host Opik?

Yes. Opik Open Source is available on GitHub for self-hosting. It includes the full feature set of the cloud versions. You can download, install, and run it your own infrastructure.

What integrations does Opik support?

Opik integrates with 60+ AI frameworks, model providers, and AI gateways, including LangChain, LlamaIndex, OpenAI, and Hugging Face. It also supports OpenTelemetry, MCP server, and multiple SDKs (Python, TypeScript).

Comet

Updated Jul 26, 2026

Log, detect, and fix AI agent errors with Opik. Open-source LLM observability and evaluation. Automatically surface errors, get code fixes, validate performance. Trusted by 150k+ developers.

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#ai evaluation#llm tracing#observability#agent testing#prompt versioning

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Editor's Verdict

Rating: 4.7/5.0•Reviewed by RAGWiki

At $0, Comet stands out as a powerful solution in the developer tools,code assistant landscape. It is especially well-suited for professionals like AI/ML Engineer and Engineering Manager. However, potential buyers should note that it might not be perfect if you are strictly trying to avoid limited free cloud tier. Overall, it offers a robust toolset that significantly accelerates workflows.

Key Takeaways

LLM Tracing
Silent Error Detection
Ollie AI Assistant
Test Suites & Evals

In-Depth Review: What is Comet?

Opik is an end-to-end AI evaluation platform that connects observability to action. It automatically turns trace data and eval results into code fixes, helping teams build agents that continuously improve and never repeat mistakes. With 60+ integrations, enterprise-grade reliability, and an open-source core, Opik is trusted by thousands of companies to ship reliable AI features.

Core Features

LLM Tracing

Log every step your agent takes with full observability, including context retrieval, tool selection, and user feedback scores, via 60+ integrations.

Silent Error Detection

Automatically surface errors from thousands of traces using Diagnostics, grouping similar recurring issues and identifying root causes without explicit error messages.

Ollie AI Assistant

Fix issues at the source with Ollie, an AI agent that understands traces and recommends fixes for tool calls, context retrieval, and system prompts.

Test Suites & Evals

Validate fixes with automated test suites and evaluations using 40+ LLM-as-a-judge metrics, golden datasets, and pass/fail assertions.

Production Monitoring

Monitor and manage agents in production with dashboards, cost tracking, governance, and alerts to catch new issues before they affect users.

Agent Playground

Configure and test agents interactively in a sandbox environment, with prompt and tool optimization capabilities.

Prompt Versioning & Library

Manage and version prompts with a built-in library, enabling evaluation and iterative improvement across agent workflows.

Pricing

Open Source

Full AI observability & agent testing feature set
True OSS: same codebase as hosted versions
Agent tracing & analysis
Test Suites & assertions
Agent Playground
Community support via Slack and GitHub
Self-hosted deployment

Free Cloud

Up to 10 team members
25k spans per month
60-day data retention
Agent tracing & analysis
Test Suites & assertions
Agent Playground
Ollie coding harness trial

Pro Cloud

$19/month

Up to 50 team members
100k spans per month
60-day data retention
Customizable monthly span limits
Customizable data retention periods
All Free Cloud features
Email support

Enterprise

Custom

Unlimited team members
Custom usage plans
Flexible deployments
Service accounts and view-only users
Single sign-on
Dedicated support and SLAs
SOC 2, ISO 27001, ISO 9001, HIPAA, and GDPR compliance
All Pro Cloud features

Pros and Cons

Pros

Open Source & TransparentOpik is truly open source with the same codebase as hosted versions, giving full control over deployment and data.
Enterprise-Grade ReliabilityBacked by Comet's infrastructure, trusted by large organizations for security and scalability.
Fast Trace IngestionThousands of LLM traces appear in the platform almost instantly for quick debugging.
Extensive Integrations60+ integrations with frameworks, model providers, and AI gateways, plus OpenTelemetry support.
Comprehensive EvaluationIncludes test suites, automated evaluations, annotation UI, and optimization algorithms for end-to-end quality.

Cons

Limited Free Cloud TierFree plan caps at 25k spans per month with only 60-day retention, which may not suffice for high-volume production use.
Advanced Features Require PaymentOllie assistant, prompt optimization, and sandbox features are trial-only or require purchasing tokens beyond free tier.
No Self-Hosted Cloud OptionOpen Source is self-hosted only; cloud versions are managed and may not meet all on-premise requirements.
Learning Curve for Complex WorkflowsSetting up evaluations, test suites, and custom metrics may require significant initial effort for new users.
Dependency on Comet EcosystemOpik is tightly integrated with Comet's MLOps platform, which might not suit teams using alternative ML experiment management tools.

Use Cases & Recommended Professions

AI/ML Engineer→ View Toolkit

Build and debug generative AI agents with full traceability, rapid error detection, and automated evaluation.

Engineering Manager→ View Toolkit

Track team spend on coding agents like Claude Code, ensure consistent performance, and gain governance over production AI.

Data Scientist→ View Toolkit

Experiment with LLM prompts, run evaluations, and compare model performance using golden datasets and metrics.

Product Manager (AI)→ View Toolkit

Monitor agent behavior in production, gather user feedback, and validate feature iterations with test suites.

Research Scientist→ View Toolkit

Conduct reproducible AI experiments with trace logging, annotation, and collaboration features for deep learning models.

DevOps / MLOps Engineer→ View Toolkit

Deploy and manage self-hosted Opik instances, integrate with existing CI/CD pipelines, and ensure compliance.

Frequently Asked Questions

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ℹ️ Curation Disclosure: The overview and features of Comet were synthesized using AI and fact-checked by our curation team to ensure accuracy.