Helicone
LLM gateway with logging, caching, and cost analytics
Verdict
Proxy-based approach means zero SDK changes — add one header and get logging, caching, and rate-limiting. One-line integration is its superpower. Managed cloud only.
Other Observability & Evals
- Arize AIStable
ML and LLM observability platform with drift detection and evaluation
- BraintrustExperimental
End-to-end LLM evaluation and experimentation platform
- LangfuseProduction
Open-source LLM engineering platform — traces, evals, prompts
- OpenLLMetryExperimental
OpenTelemetry-based observability for LLMs
- Phoenix (Arize)Stable
Open-source AI observability with embedding and RAG tracing
- PromptLayerStable
Prompt version control, A/B testing, and analytics platform