Helicone and Opik by Comet are leading open-source platforms designed to monitor, evaluate, and optimize the performance of Large Language Model (LLM) applications, each offering unique strengths tailored to different user needs. Helicone is noted for its ease of setup, intuitive user interface, and comprehensive features like built-in caching, cost tracking, and extensive security measures, making it ideal for cross-functional teams including non-technical members. It supports broad integration with major LLM providers and third-party tools without requiring an SDK. Opik, on the other hand, excels in robust automated scoring and deep integration within the Comet ecosystem, favoring code-driven workflows suitable for those deeply involved in AI evaluation. Both platforms provide generous free tiers and are GDPR and HIPAA compliant, allowing users to experiment with their features to determine the best fit for their specific workflow and team composition.