Helicone vs Comet: Best Open-Source LLM Evaluation Platform

As your Large Language Model (LLM) application goes into production, you need reliable observability tools to track, debug, and optimize model performance.

Enter Helicone and Opik (by Comet), two leading open-source LLM evaluation platforms, each offering unique capabilities tailored to different use cases.

This article compares their features, integrations, and strengths to help you determine which tool is the best fit for you.

How is Helicone different?

1. Helicone is easy to set up

Helicone's key strengths lie in its extremely simple setup for the cloud offering, built-in caching, and intuitive prompt experimentation and evaluation features to optimize application performance.

Beyond the easy developer experience, we try to be as transparent as possible about our pricing. You do not need to provide your credit card to try the free tier.

See our API Cost Calculator for a rough estimate of how much you can save with different model providers.

2. Helicone is designed for teams

Helicone is a complete observability tool that covers the full LLM lifecycle, from logging and experimentation to evaluation and deployment. Opik shares similar features as Helicone but requires more coding to use.

Helicone is more suited for cross-functional teams given the ability to have non-technical members involved in prompt design and evaluation.

At a Glance: Helicone vs. Opik by Comet

Platform

LLM Evaluation

LLM Monitoring

Security, Compliance, Privacy

Helicone: Best for Multi-Functional Teams

What is Helicone?

Helicone is an open-source observability platform designed for developers and teams building production-ready LLM applications. It covers the full LLM lifecycle, from logging and experimentation to evaluation and deployment.

Key Features

• 1-Line Integration: Get started quickly with a one-line proxy setup.
• Response Caching: Reduce API costs and latency with simple header-based caching.
• Prompt Experimentation & Evaluation: Test and refine prompts and run experiments all via an intuitive UI.
• Webhooks & Alerts: Automate LLM workflows, trigger actions, and get alerts for critical events—never miss a beat.
• Flexible Pricing: Transparent pricing with a generous free tier to explore most features.

Why Developers Choose Helicone

• Simple & Developer-Friendly: Intuitive setup and integration. Very user-friendly.
• Extensive Compatibility: Works with all major LLM providers, orchestration frameworks, and third-party tools like PostHog.
• Cost Efficiency: Built-in caching and cost tracking help cut down on API expenses.
• In-Depth Analytics: Provides rich insights into API performance, user activity, and overall usage trends.

How to Integrate with Helicone

Integration is available for all providers.

import OpenAI from "openai";

const openai = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY,
  baseURL: "https://oai.helicone.ai/v1",
  defaultHeaders: {
    "Helicone-Auth": `Bearer ${process.env.HELICONE_API_KEY}`,
  },
});

For other providers, check out the documentation.

Opik by Comet: Comprehensive Evaluation & Scoring

What is Opik?

Opik by Comet is an observability tool that focuses on experimentation and automated evaluation. It integrates with the broader CometML ecosystem and largely supports code-based workflows.

Key Features

• Automated Scoring: Robust automation scoring capabilities.
• Deep Comet Integration: Ideal for teams already using Comet's ML observability tools.
• Code-Based Experimentation: Provides fine-grained control over AI evaluation.
• LLM Tracing: Provides insights into multi-step and multi-LLM workflows.

Why Developers Choose Opik

• Strong Evaluation Capabilities: Out-of-the-box support for robust automated evaluation workflows.
• Deep CometML Integration: Seamlessly integrates with the Comet ecosystem, including broader ML experimentation and tracking tools.

How Opik Compares to Helicone

Which LLM evaluation platform should you choose?

Both platforms are excellent choices for monitoring and optimizing LLM applications. Here's a quick guide to help you decide:

• Choose Helicone if you want a full observability suite with easy setup, caching, cost tracking, and security. It's ideal for cross-functional teams that need a mix of no-code UI and developer-friendly tools.
• Choose Opik if you're mainly focused on AI evaluation and need robust automated scoring with fine-grained, code-based control.
• Choose Helicone if your team includes non-technical members involved in building and managing the application.
• Choose Opik if you need a strong integration with the Comet ecosystem.

Both are open-source with free tiers—so you can try both and decide based on your workflow!

Additional Resources

• Comparing Helicone with Langfuse

• How Helicone Compares to Arize Phoenix

• A Deep Dive Into Helicone Features

Frequently Asked Questions (FAQs)

1. Which platform is easier to set up?

Helicone is easier to integrate since it only requires adding headers to API calls. Opik, on the other hand, requires an SDK and more configuration to get started.

2. Which platform has better cost tracking?

Helicone provides a centralized dashboard with detailed cost tracking and analysis. Opik offers basic cost tracking and lacks the same level of visualization.

3. Which platform has better prompt management?

Both platforms support prompt versioning and tracking, but Helicone offers a more feature-rich playground with better UI-driven prompt experimentation.

4. Which platform is better for evaluating LLM performance?

Both Helicone and Opik support human, automated, and LLM-as-a-judge evaluations with custom evaluation metrics. However, Opik has better automated scoring, while Helicone allows integration with LastMile for fine-tuned evaluations.

5. Does either platform support caching?

Yes, Helicone provides built-in caching to reduce API costs and latency. Opik does not offer caching.

6. Which platform is better for large-scale integrations?

Helicone supports more integrations with third-party tools, orchestration frameworks, and model providers. Opik has fewer integrations.

7. Which platform offers better security?

Helicone provides robust security features, including Key Vault for secure API key management and Prompt Armor for enhanced security. Opik has limited security features.