Quick answer: Open-source LLM observability — drop-in proxy for logs + analytics.
Helicone is an open-source LLM observability platform built by Helicone that provides real-time logging, monitoring, and analytics for language model applications. It functions as a drop-in proxy that sits between your application and LLM APIs, capturing detailed metrics without requiring code changes. The platform tracks token usage, latency, costs, and error rates across multiple LLM providers including OpenAI, Anthropic, and others. Helicone offers both a free tier for developers and premium features for teams managing production AI workloads. It's designed for developers who need visibility into LLM behavior, cost optimization, and debugging capabilities without the overhead of complex infrastructure.