Helicone is an open-source LLM observability platform that takes a uniquely simple approach to monitoring AI applications. Instead of requiring SDK integration or code changes, developers simply change their API base URL to route LLM requests through Helicone's proxy, instantly enabling comprehensive observability.
The proxy approach means Helicone works with any LLM provider — OpenAI, Anthropic, Google, and over 300 other model providers — with zero code changes beyond the URL swap. This has made it one of the fastest-growing observability platforms, processing over 2 billion LLM interactions.
Core features include request and response logging, cost tracking across models and users, latency monitoring, response caching for cost reduction, rate limiting for usage control, and user-level analytics. The dashboard provides real-time visibility into all LLM usage across an organization.
Additional capabilities include prompt experimentation for A/B testing different prompts, evaluation tools for measuring output quality, and a gateway that adds routing, fallback, and retry logic to LLM requests.
Helicone is open-source and can be self-hosted. The managed cloud offers a generous free tier with paid plans for higher volumes and advanced features. The simplicity of the proxy integration makes it particularly attractive for teams wanting observability without heavy instrumentation.